As said bad players are bad players regardless of what's in front of them. This is pretty much the whole "controller vs M&K" argument as well, where people say:
"Controllers players are naturally worse than people who use mouse & keyboard."
In all honesty though, I've seen some pretty terrible people in MMORPGs using this setup just as much as any other setup. It's the exact reason SE incorporated macros, which both sides of the fence utilized and more games are starting to introduce ;p So you can't really say someone's performance will be hindered heavily/a lot when there's people being pretty bad with the most efficient setup in front of them and again, i honestly seen worse M&K players than gamepad players which GP is basically emulating "menu navigation".
As do I.
