For a start, I'll say that this site has definitely improved my chess. And I am enjoying my stay, as well. Yes I am!
And as for the lack of knowledge of players here...
I myself lack a lot of knowledge, and since there are a lot of players here who are far up ahead, I intend to stay here for quite a while, as long as I can learn from them...
No matter what controversy stirs over the rating systems, the differences between on-line and "live" chess or the so called knowledge "gaps" between those on this site and others, has Chess.com elevated your chess game? And are you enjoying your "stay"?
I for one have seen my chess game elevated - where else can you play against such a wide variety of players from all over the world from the comfort of your own home? Where else are you exposed to people with a significant common thread in their life? The benefits of this site to my game and more importantly my life far outweight that of my rating and / or the supposed lack of knowledge of the players here....