What is the purpose of old-school D&D class level limitations? [closed]

Question

When I played 1E and 2E, racial level limits was one of the first rules we decided to ignore. We decided that it would prevent us from playing (say) an Elven fighter for as long as the party might last and that we couldn't figure out a reason for the rule to exist. Now I'm thinking about teaching some young relatives to play D&D, and I'm pretty sure that I want to go with 2E, which I know best and learned at their age. I might use 2E itself, or maybe OSRIC. I'm re-evaluating a lot of the rules that I used to ignore, and that's one that I'm curious about.

What is the purpose of that rule? Is it for balance, or flavor, or something else? A well-explained opinion is welcome, but I'd love to see historical evidence from the designers.

Answer 1

E. Gary Gygax notes in several places that the class limits and level limits were both game balance and to force the game to be humanocentric.

I'll let EGG speak for himself (Dragon #29, Sept. 1979, p. 12):

The character races in the AD&D system were selected with care. They give variety of approach, but any player selecting a non-human (part- or demi-human) character does not have any real advantage. True, some of those racial types give short-term advantages to the players who choose them, but in the long run, these same characters are at an equal disadvantage when compared to human characters with the same number of experience points. This was, in fact, designed into the game. The variety of approach makes role selection more interesting. Players must weigh advantages and disadvantages carefully before opting for character race, human or otherwise. It is in vogue in some campaigns to remove restrictions on demi-humans — or at least relax them somewhat. While this might make the DM popular for a time with those participants with dwarven fighters of high level, or eleven wizards of vast power, it will eventually consign the campaign as a whole to one in which the only races will be non-human. Dwarves, elves, et al will have all the advantages and no real disadvantages, so the majority of players will select those races, and humankind will disappear from the realm of player character types. This bears upon the various hybrid racial types, as well.

While I disagree with his conclusions, His point is pretty clear: He felt it important to nerf demi-humans so as to force players to choose humans in preference to them.

It's been asserted that Gygax ran high-level games, citing Tomb of Horrors. The S1 module with vermillion cover lists no levels on it for players, but includes mostly done pregens; the green cover shows levels 10-14. The highest level characters included are a 14th level cleric and 14th level mage; the lowest, a halfling fighter/thief 4/5. Definitely more evidence that Gary's idea of High level was rather low by modern 36-leve (BXCMI), 30-level (4E) or 40 level (3E/3.5E) games.

Frank Mentzer (ExTSR) makes an important point in understanding why the initial restrictions were so severe... From his comment in response to this answer:

Remember that when the RPG biz began, roleplaying a non-human was a major stretch. Up until then, in assorted wargames & minis games, everybody was playing humans, period. We've broadened a lot over the years.

It should be noted that Chainmail was one of the earliest minis games to have non-human hominids, and strongly appears to be the earliest, with a 1971 release. (Source: Board Game Geek database multiple searches on 25 May 2011.) D&D follows in it's Chainmail roots.

To put in perspective, the original little book set only covers to about level 15. Gary Gygax commented that, generally, his campaigns only ran to about levels 12-14. Old Grognard on RPGNet, who played in Gary's group, confirms this as well, as did Dave Arneson. The concepts of level in many newer editions are very different now than what Gary was using in his own games. Just looking at AD&D & Moldvay/Cook vs earlier editions shows level creep.

Likewise, several other early game designers generally considered 9th level time to hang up the armor and settle down. T&T only covers to level 15. The Arcanum to level 20. Palladium to level 15. Bushido to level 6.

To show the progression of the level limits even during EGG's day; multi-class combos allowed shown as slashes. C=Cleric F=Fighter, Mu=Mage, T=Thief P=Paladin Mk=Monk A=Assassin D=Druid. The Number is max level, a hyphen indicates maximum with high stats, and parenthesis indicates NPC only.

^{OD&D, no Supps (V1 p6-8):
Human: F∞ C∞ Mu∞
Dwarf: C7 F6-8 T∞ F6/T∞
Elf: F4 Mu6 F4/Mu6
Halfling: F4}

^{OD&D + Supp 1:
Human: F∞ C∞ M∞ T∞ P∞
Dwarf: C7 F6-8 T∞ F6/T∞ P6-8
Elf: F4-6 Mu6-9 C6 T∞ F4-6/Mu6-9/T∞ P6-8
Halfling: F∞ T∞ P6-8
Half-Elf: F6-8 Mu6-8 T∞ F6-8/Mu6-8 F6-8/Mu6-8/C4 P6-8
Note: Due to wording on page 8, no racial restriction exists on Paladins are present; that was errata corrected promptly...
Also note that the number of demi-human options grew exponentially}

^{OD&D + Supp 1 & 2:
Human: F∞ C∞ Mu∞ T∞ P∞ Mk16 A13
Dwarf: C7 F6-8 T∞ F6/T∞ P6-8
Elf: F4-6 Mu6-9 C6 T∞ F4-6/Mu6-9/T∞ P6-8
Halfling: F∞ T∞ P6-8
Half-Elf: F6-8 Mu6-8 T∞ F6-8/Mu6-8 F6-8/Mu6-8/C4 P6-8
Note: No errata for S1 was included...}

^{OD&D + Supp 1, 2 & 3:
Human: F∞ C∞ Mu∞ T∞ P∞ Mk16 A13 D12
Dwarf: C7 F6-8 T∞ F6/T∞ P6-8
Elf: F4-6 Mu6-9 C6 T∞ F4-6/Mu6-9/T∞ P6-8
Halfling: F∞ T∞ P6-8
Half-Elf: F6-8 Mu6-8 T∞ F6-8/Mu6-8 F6-8/Mu6-8/C4 P6-8
Note: No errata for S1 was included, here, either}

^{AD&D 1E
all multiclasses are limited in level to the same levels in each class as single classed. Human: C∞ D12 F∞ P∞ R∞ MU∞ T∞ A13 Mk16
Dwarf: (C8) F7-9 T∞ A9 F/T
Elf: (C7) F5-7 MU9-11 T∞ A19 F/Mu F/T F/MU/T MU/T
Gnome: (C7) F5-6 Il5-7 T∞ A8 F/Il F/T Il/T
Half-Elf: C5 F6-8 R6-8 MU6-8 T∞ A11 C/F C/F/MU C/R C/MU F/MU F/T F/MU/T MU/T
Halfling: (D6) F4-6 T∞ F/T
Half-Orc: C4 F10 T6-8 A∞ C/F C/T F/T F/A}

As an aside, exceeding AD&D racial caps was allowed starting with the Unearthed Arcana sourcebook.

Answer 2

There were a few reasons, some based in mechanics-logic, other more setting-logic specific.

The first is simple. As Gary said in the AD&D DMG, his game was human-centric. He came right out and said it.

Advanced D&D is unquestionably "humanocentric", with demi-humans, semi-humans and humanoids in various orbits about the sun of humanity. Men are the worst monsters, particularly high-level characters ... There is a point where the well-equipped, high-level party of adventurers can challenge a demon prince, an arch-devil, or a demi-god. While there might well be some near or part humans with the group so doing, it is certain that the leaders will be human. ... The game features humankind for a reason. It is the most logical basis in an illogical game. (DMG, p. 21)

As was mentioned in a few dragon magazine articles, the other races lived longer, and so once someone creates a setting with much logical bias, by sheer virtue of the length of lifespan, the elves have more 20-30th level characters of all classes if you don't have the racial limits. The longer a class-capable npc/character lives, the higher level they can become.
It's hard to have a human-centric game where logic dictates the humans don't live long enough to compete with the the other races, so we have the level caps for other races.

The second reason is more mechanical. Other races get bonuses and abilities that humans don't, that are especially useful at low levels. Infravision, detection of secret doors, better saves versus poison, etc. The Humans were 'game balanced' in that they were not as good at low levels in some ways, but were a better long-term choice.
This is also the reason they were allowed to be any class. Because it actually makes no sense in terms of setting logic; a race with no clerics or no magic-users would get wiped out pretty quickly by other races, but in terms of game balance, it makes humans a decent choice for the type of game AD&D was created for, the long campaign.

Answer 3

The reason was pretty clear, Gygax wanted to keep the game from turning into a demi-human only game. (See the Dragon Magazine quote in @aramis' answer), the key point being:

it will eventually consign the campaign as a whole to one in which the only races will be non-human. Dwarves, elves, et al will have all the advantages and no real disadvantages, so the majority of players will select those races, and humankind will disappear from the realm of player character types.

I just allowed humans to put +1 to any one ability at creation and gain +15% exp bonus and then ditched demi-human level caps. I've been tempted to allow humans to be multi-class but no one has ever asked and I'm not sure what combinations I'd disallow.