That's just silly. Not everyone in LFR is bad or doesn't want to improve.
I used to raid heroic ICC and did Ulduar hardmode bosses. I quit during Cata, but I came back for Mist. Right now I only raid LFR because I can't commit to a regular schedule for a raiding guild because of odd working times. I work a different shift every month, so I would have to be hopping guilds every month if I wanted to raid anything other than LFR. Just because I raid LFR doesn't mean I shouldn't be the best I can be, which is why I am here regularly on the forums.