I am this guy.
I play D&D 3.5 but I expect the experience to be generic.
I know some players who just pick an off-the-shelf character and roll with it; deciding on their options as they go. Essentially, they see the mechanics of character creation as a chore and prefer to move on to actual play. It's fine by me, I like playing with them...
... but I prefer my characters to have a bit more depth.
For me, character creation is fun. I'll got back and forth between races, templates, bloodlines, classes, traits, feats, flaws, skill tricks, familiars/animal companions, items and fluff until I find a point where everything meshes together; where the mechanics and the fluff are in line. It's a lengthy process, sometimes requiring a week or two just to get the first 5 levels planned fully and a rough sketch of the next levels.
Oh, and I am not above using early entry tricks either, nor am I above asking the DM if some requirements may be waived (rarely though)... and yes I sometimes use/create homebrew.
Could the DM know about every single option my character uses?
Yes, but honestly the investment would be huge. And there's another player like me in the group.
So instead, we proceed differently. We present a concept to the DM and the party, which they approve (generally), and the DM leaves the mechanics up to us, with the understanding that we have researched the rules fully and will make sure to follow them.
It's our responsibility to be on top of our characters.
With some players playing off-the-shelves characters and others playing highly customized/researched characters, what of group balance?
Our group is not balanced, and there is no issue.
As most role-playing games, D&D has roles. Every character specializes in fulfilling a number of roles, some they'll be the best at, some they'll be able to support others in and some they'll just do a poor job in. There are many roles: crowd control, crowd damage, focused control, focused damage, party face, party support, scout (infiltrator/sentry/tracker), skill monkey, ...
Not all campaigns give all the roles an equal share in the spotlight, but all campaigns should give the opportunity to a couple of roles to shine. When starting on a campaign it should be made clear what situations will occur (and their frequency)... though normally the theme is sufficient to get the idea.
It is generally expected that these roles will be distributed somewhat in the party: the Barbarian is a front-line fighter, specializing in focused damage; the Bard is the party face and party support, jack of all trades and master of none; ...
It does not matter that all characters are not on an equal footing, what matters is that:
- at any point, all characters should be able to contribute (if a little)
- most of the times, all characters should be able to contribute well
- regularly, each character has a chance to contribute greatly (be in the spotlight)
In my current party, this is accomplished by my character excelling at absorbing damage and crowd control. None of the other characters were controlling crowds, and none were willing to play the meat-shield. They care little that my character excels at it, all that matters to them is that they can play their characters in the way they want!
It's okay for an optimized character to play in an unbalanced party as long as (a) the party accepts it and (b) the others still have ample room to shine; it's easier if this character fills a vacant role.
But this character is so optimized it's blazing through all encounters!
That's an issue.
All characters should have ample room to shine... without the OP'ed character holding back.
This can be taken up with the player, asking him/her to introduce a flaw. Personally, I like flaws, I think they give some depth.
I often joke that my current character is blind-deaf. She's not... but she has such a low perception that she's always the last to pick up on things. And she's a bit naive. That makes her the natural target for an ambush (from foes) or a prank (from friends).
The "optimized" character should have at least one glaring flaw. An obvious string to pull by the DM if need be, it can also be a comic relief.
I think the underlying point here is that role-playing is a group activity; all members of the group should have fun playing, and all members of the group should therefore work toward enabling others to have fun with the understanding that others are working toward enabling their own fun.
I do not see the custom/homebrew/optimized character as an issue per se. There are many characters that can hamper everyone's fun (a Wizard never knowing her spells, a Druid never knowing the stats of her summoned animals, ...), and in all cases it's just the player's responsibility to make sure not to drag the others' fun down.