Myself, I've been a member of this and previous incarnations of this board since the late 90's, so a very long time. I used to post a lot more and over the years have been involved in many discussions and quite a few full blown arguments with a number of (almost invariably) rightwing individuals and/or trolls, one or two of which still resurface every now and then. HOWEVER, the main reason of me being here has always been keeping in touch with people I know in real life: I have no problem saying I'm not the most sociable person on the planet, generally speaking I don't talk to strangers in real life, so I don't see why I should do it on the internet.
So what's changed? In a word: Facebook. I don't mean the NMA page, I'm even less active there than I'm here. And of course I'm aware of all the shit things facebook is and does, but for all its faults it allows you to 'pick' the people you interact with (in my case almost invariably real-life friends or people I've at least met in person a couple of times) and talk to, and leave all those you don't like or have any interest talking to out.
It seems in the last few years quite a few of the old posters and people I actually see and meet up with at gigs have made the same choice as I have, we keep in touch, talk about various things, have our banter, organise meet ups etc. Some of them still post here sometimes, but like me less and less often, and of course there are a couple of the current regular posters here I have met in real life but are not on fb, but not that many at present, so while I still like coming back and reading posts every now and then, I don't tend to be very active anymore, and I don't expect things to change anytime soon.