I read a ton of the threads here. But I don't post on a lot of them.
There are a couple of reasons.
There's the Back-Away-Very-Slowly threads. The threads that you just know are going to turn into something ugly - political threads, that spanking thread.
There's the I-need-advice threads. Most of the time, by the time I read everything, someone has already given the advice I would have given, so there's no need to post.
There's the Help threads. Most of the time, the question is answered by the time I read it or I don't know the answer anyway.
This pretty much sums up how I feel about posting.