a better understanding of the fights

Disagree. I know from the outset whether I'm going to help or carry. I'm the deciding factor. I run a weekly flex group for the non-core members of my guild and alts (shout out to the forum peeps who came last night!). We wipe, I explain what went wrong try to explain unfamiliar roles, earnestly hope that people come out of the run with some gear and a better understanding of the fights. That's me when I'm helping.
euwowgold.fr
When I feel like carrying (which is rare, if ever), I go in and if I see someone sucking I shrug it off unless it's holding the group back. Then they either get kicked or I leave. There are a few fights in SoO N that my guild can 9-man at this point, like Immersius. If one of the core members is late that night, we can just go in as 9 and kill it; however, we usually offer a carry to the guild at large if anyone wants to come for a shot at gear off that boss. It literally doesn't matter if they spend the whole fight face down on the ground.