Yeah, that's true. Though, I think both ends of that spectrum are hard to deal with. As with many things, there's a vast middle ground that works better than either end: Know the game well enough to play it without bogging it down for others, but also, don't bog it down for others by your vast knowledge of every little detail either.
I have a problem player right now who's kind of the worst of both (Though a good guy! I wouldn't want to kick him out or anything!) He doesn't know the rules of the game particularly well, but he wants to optimize his every turn for the most "perfect" thing he can do. He takes as long on each of his turns as the rest of the table combined, going through all his spells and humming and hawing as to which would be the best one.
I'm like, "Just pick one and cast it! It doesn't usually matter that much, in the end."
I'm going to keep working on trying to get him to "behave".
"Play nicely with others" (my #1 piece of advice in gaming) has a LOT of nuance, really.