Tanks are probably the only ones getting screwed out of the deal here.
Only shitty tanks are screwed. Good tanks do not try to be the least usefull as possible.
Nah in fact, good players in general try to perform their role as best as they are able to.
I'm pretty tolerant toward low standard dps, as long as it does not has consequences.
Still, it is not ellitis to expect a minimum from team mates. Having them endure a nice reality slap in their face is good from time to time.
Stop defending every one. When you queue in a lvl 60 content with lvl 50 weapon, you are NOT defendable.

And I approve the idea of being unable to equip a piece of gear below the minimum lvl required for the duty. Gearing up in this game is far too easy to allow such behaviors.