It's why I play BLM when I do expert roulette. I don't trust the other DPS to carry their weight and AoE.

I know it's painful to see--for example, a BLM not doing AoEs (Seriously, I've had a few BLMs that didn't AoE and the reason was because "it had less potency" and ignoring the fact that it's an AoE) but it's not a good reason to kick them just for that though. You should put that effort onto correcting them.