iLVL alone dictates who is qualified, like you don’t want to take someone at 170 iLVL for an M10 unless you know them or what they can do, and even than they might just not have the DPS to even pass the dungeon. But at the same time I have seen 200 iLVL players in an M9 who were terrible.
We need more, plain and simple, more information so we can be best informed about the actual skill of a player.