Quantar -
I too have seen many an MP that seem to think that looting chests, running into rooms with 2-3 mobs is ok, like they are invulnerable. It's not the norm, but it happens, and usually seems to be them that blame a doc who's still trying to buff everyone in the entrance and told the team they arent ready for their death
Communication (then listening) helps every team, and just running off like a damn fool gets you killed/kicked