There are several reasons, but first and foremost, I'm spending WAY too much time on these sites and it does NOTHING for me in real life. If anything, it's only an aggravating test of my patience half the time. I can't post mumms and I refuse to get them reinstated, I've been banned from a lounge just for being my usual sarcastic self and I refuse to even enter a lounge again (you invite me, I block you), and there are other issues I'm sure the admin is tired of hearing. Bright Eyed Artist put it so well in her blog http://fubar.com/blog/84553/704000 .
Anyway, nothing personal, but I have other things to do.