Some people who play healers are also disabled and choose healing because it is a less intensive job than most DPS jobs (I know a couple people like this. They stick to healing or Tank jobs because they're easier to manage.) We should be mindful that there are players who aren't going to be able to perform at "100% capacity" for various reasons, and since dungeons are not really progression or hardcore content, as players I think it would behoove us to not immediately start screaming at people for "not doing their job".
Now if someone puts themselves into progression endgame content (8 man raids, EX Primals, etc.) - then that's a definite time for scrutiny. You should be doing your best in those situations.
But just because they're not assisting in speeding a dungeon run up by 5 minutes is no reason to be a jerk.
