To be clear, it's definitely about the power gamer play style for me and not about the individual player.
Don't forget that, as GM, you have a lot of control over this. For example, I'm an ogre when it comes to rolling up stats. I play it RAW (for the Conan game) and don't make any exceptions. The book says 4d6, drop lowest, six times, then arrange to taste, and that's the way it happens in my game.
I'm all for people maximizing their characters given what they have to work with. But, I also reward good roleplaying. And, it's hard for that maximizer to get too many bonuses if he threw some low or mediocre stats.
The GM can hamper optimizers in other ways, too, so that their characters don't get too out of hand.
For example, my game focusses on a clan of Barbarians (Cimmerians, like Conan). They don't even put locks on their doors in the village. So, I've barred the Open Lock skill. A character cannot get it at this time (he'll have to search it out in the game).
Plus, don't forget the training rules in the 3.5 DMG. This gives you another tool in the game to keep optimizers from growing their characters in a non-roleplaying oriented way.
Ultimately, I think I've come to understand the power gamer mindset a little better...
It's the same mindset used when people buy a single player computer game then download a "cheat" for it. People like to "win".
I feel that those people are not getting everything out of a roleplaying game that there is to get.
I don't think those types of gamers play the same type of game that I do. They're playing a "game", while I'm trying to "live" in a fantasy world.
Do you just avoid gaming with people who have play styles that you don't enjoy?
Yes. Absolutely.
It's true that it is sometimes hard to find players. But, at the same time, I'd much rather play with a "good" (someone who appreciates the game in the same way as I do) player than someone that just frustrates me or bores me.
Right now, I've got three players in my current group. Two are strong roleplayers, and I'd play a one-on-one with either of them anytime. One is a poor-to-moderate roleplayer, optimizer, and seems to me to be playing the game the same way he would a first-person shooter computer game. He's "OK" with the other two. They're good influences on him. But, I'd never play a one-on-one game with him. It just wouldn't be any fun.
And, there's another player I've played a couple of sessions once who wants to come play with us, but I just don't like his play style. He hasn't got a roleplaying bone in his body. He's a total rollplayer.
He doesn't "mesh" with the group, and he would not add anything (and probably detract) if I let him join us. So, I've polietly come up with excuses to stave him off. I don't want to hurt his feelings, but I'm not going to let him join us, either.