I registered to GTAF about 2 years ago, but I haven't been on it in a long time as a registered user. I have, however, visited the site recently to look at the downloads for GTA San Andreas and Vice City, I did download a few but I only used them once.
It isn't the users of GTA Forums that are the problem, it's the way they are treated on there, there's a lot more freedom of speech here than there is on GTANet, You're less likely to be banned for saying that you hate GTAIV or ice-cream on here than you would on most of TGTAP's counterparts.
Luckily I haven't been banned yet, I've only really made 5 or 6 posts on there but I guess that might be the average number of posts or thereof for members who have been banned.