It depends whether you are just talking about D&D or not. In most variants of D&D, combat is what most of the rules revolve around, with only complex skill checks or skill challenges providing more in depth meat to other activities (social, investigation, etc.) Some people prefer this and like handling those other things via player-GM interaction and not rules per se.

Many other games, however, have one or more of the following attributes:

1. Much simpler combat rules or are very rules light in the first place, which closes the "gap"
2. Specific detailed rules for other important non-combat activities
3. A unified mechanic where combat is treated exactly the same as other activities

As an example of #1, the Amber Diceless RPG. Every character has only a couple stats, characters are the only meaningful challenge for each other, and one character has a Warfare score higher than the others, so there's not really crunchy multi-round combat and other activities are way more important. Or the Jenga-powered Dread RPG, where whatever action you try is adjudicated by a pull form a Jenga tower, not a multiround combat mechanism.

For an example of #2, in the "Aces & Eights" Western RPG, there are complex combat rules, but there are also large complex and crunchy rule sets for prospecting, trials, and cattle drives. This is a different design approach, that says "Whatever is super important, make a big ol' ruleset for it."

#3 is probably best demonstrated by the FATE system, to cite a specific implementation the Dresden Files RPG. Characters have physical, mental, and social stress and combat isn't really treated any differently from other activities; you could do a round by round battle of wits doing mental stress just like you could a combat doing physical stress (this is overly simplified, but who cares).

It depends whether you are just talking about D&D or not. In most variants of D&D, combat is what most of the rules revolve around, with only complex skill checks or skill challenges providing more in depth meat to other activities (social, investigation, etc.) Some people prefer this and like handling those other things via player-GM interaction and not rules per se.

Many other games, however, have one or more of the following attributes:

1. Much simpler combat rules or are very rules light in the first place, which closes the "gap"
2. Specific detailed rules for other important non-combat activities
3. A unified mechanic where combat is treated exactly the same as other activities

As an example of #1, the Amber Diceless RPG. Every character has only a couple stats, characters are the only meaningful challenge for each other, and one character has a Warfare score higher than the others, so there's not really crunchy multi-round combat and other activities are way more important. Or the Jenga-powered Dread RPG, where whatever action you try is adjudicated by a pull form a Jenga tower, not a multiround combat mechanism. Basically, some games "reduce fights to a single roll too." Storygames tend to like this.

For an example of #2, in the "Aces & Eights" Western RPG, there are complex combat rules, but there are also large complex and crunchy rule sets for prospecting, trials, and cattle drives. This is a different design approach, that says "Whatever is super important, make a big ol' ruleset for it." Activities deemed unimportant get one roll or just aren't explicitly addressed.

#3 is probably best demonstrated by the FATE system, to cite a specific implementation the Dresden Files RPG. Characters have physical, mental, and social stress and combat isn't really treated any differently from other activities; you could do a round by round battle of wits doing mental stress just like you could a combat doing physical stress or a seduction using social stress. This makes all activities reasonably parallel in terms of resolution and complexity.