(opinion)
A player who's only active for 20% of a dungeon should never get a commandation. That player isn't even trying.
Opening the commandation menu, clicking on that player's name, and then clicking okay takes more efforts that the total efforts this player put in the whole dungeon.
(/opinion)
I guess some people are softer when it comes to carrying others. Kudos to you, I can't stand that. Not only they wouldn't get a commandation, but I'd initiate a votekick too after asking "Hey, can you do something?" and they answer "No".
Oh come on, you know what I meant.