Lots of members have quit posting but scan the site, and the reason I've heard is almost always Infolinks.
A few did get bothered by argumentative posts or replies.
It's unfortunate, because not only were most of those folks informative and/or fun to banter with, but younger guys won't get the benefit if accurate info from them.
I figure that while no forum is perfect, this one's the best, and I hope to either learn something or be helpful every time I check in.