Disabled players clears hardest content in the game.
Just a way to say you can go higher than you believe.

Other than that, a good 80% of the game is accessible and you wont have trouble clearing it.

Forum, don't torch me, but you can play RDM ignoring most abilities and only using the one you like.
As long as it's story content and normal mode raid, I don't believe there is a problem, no one can kick you because of low DPS.

Disabled or not, hard content is for the people dedicated to it. It won't impact your experience if you can't play it.