Final Fantasy XI or the staggered progression of World of Warcraft. It's always made more difficult, however, when someone doesn't understand what he's supposed to be doing. Sometimes, even instructional videos, pseudo-Gregorian chants, and screaming epithets over ventrilo will all fail to get someone to realize that he needs to stay put during Flame Wreath. And there are only so many times a group can take failure when there's an obvious weak link in the chain.
On the one hand, we've all had one or two things that we know we ought to do, but we're just not quite capable of doing reliably. On the other, there comes a point when the rest of the group is paying for one person's persistent mistakes. So how do you handle that one guy who can't seem to get what he's supposed to be doing? Do you try and get him kicked out? Kick yourself out pre-emptively? Or do you just resort to blaming him for any and all failures?