Yeah just no.
This is a game, unless you are suffering from some legitimate mental/physical disability there is absolutely no reason to not be able to do well.
Anything else is just a poor excuse. You can literally spend 5 minutes skimming through your classes spell priorities/reforges/proper spec/gems and do just fine. Nobody expects you to go in and do your classes highest theorycrafted dps.
I have done hundreds of LFD's since it's implementation, and I very seldom see somebody get kicked for bad dps unless they are literally doing like 5k.
And why do you think I have the obligation to teach you? Why should I have to research your class for you? Because you are too lazy and have "to much work"? That isn't my problem.
You have all the tools available to you to be a better player, if you don't choose to utilize them, don't blame people for not wanting to group with you.