Right, I was kind of thinking in terms of players. I mean, with 4e you have the 'balance thing' where you pretty much need each class to have equal ability to move the mechanical -> fictional levers of the game. A character which cannot hit often enough, or get enough successes in SCs, or put forward sufficient 'plot resources' to offer fiction-altering effect is going to languish. They will not have spotlight time, effectively. In the 4e design this is pretty tweaky, if you have a 15 in your Prime Requisite, you've pretty much gimped yourself for life.
DW is much less extreme. Sure, if you get some wonky playbook online that gives you the kitchen sink, or your 5 levels ahead of the rest of the party, then there will be a tendency to hog the narrative and push it what way you want, but the GM has ample ways, and so do the other players, to simply allow more moves from others, or at least insure that everyone gets consequential move opportunities thrown at them, etc. And certainly the GM can always chew harder on the guy who sticks out. If he's always the tough guy, the dragon always bites him! There are few strictures in the game in terms of how that falls out, unlike 4e where if you aren't where the dragon can take a bite at you, you're not going to get whacked on, and at worst the rules tend to even out the consequences.
I'm guessing that even if, say, the Wizard in this game of yours is more capable than the other PCs, that he can only have so much impact, and he'll rapidly burn these various resources and end up stuck hiding in a corner half the time. Like maybe your playbook has an impact on how often you act overtly and how big an impact each action ends up having, but nobody will really push the story around to higher degree, except by good management of all those spinning plates.