jasper
Rotten DM
yawn...I feel like you are generalizing the term powergamer to much. Power Gaming/ers to me, are people who like to optimize their build in anyway. Maybe they power game towards social encounters, or out of combat abilities. And of course there are some who do combat focused builds. Just because they optimize, does not mean they think the DM is their slave, or that the game has to be a certain way. As a DM your job above all else to have fun, and make sure your players do as well without catering to one type of player. If anyone intentionally gets in the way of that, it should be discussed and they should either act appropriately or be politely removed. Being a powergamer does not auto-justify removal I think. If you have a session 0 and the players discuss what they want and you find a compromise and there is still problems, it's not a power gamer's fault or role player's fault, it's a PERSON's fault. It seems like you've just encounteredpeople. I don't think anyone should be ostracized for their play style.
Power gamers. People who build their pcs to try to break the game, dm, etc. They don't compromise. And will use social methods to get their way. AKA "well if it can't Peter Parker the Purple Paladin of Pittsburgh from splat book 671-176 I not going to play and since I'm Jake's ride. It is going to suck next Friday when two of us don't show."
Optimizer. People who build their pcs to just go to edge of a superior build but don't tick off the dm. AKA "ok Jasper does not like the splat book from Morris Munchkin Press. I just use the player handbook."
Of course I was stupid for 30 years and allowed power gamers, rules lawyers, and just some sleazy people join my table just so I could game.