I'm with these forums since around 11 years now, 90% and more of the time in GT. I see no problem with detoriating manners here, quite the opposite: it has been much worse at various times in the past (and due to the moire controversial ways of goings maybe also more active, vivid, personally engaged). I would even say that currently, this year and having started in the past year, GT even has become a relatively tame place, even lame compared to those hot years the old hands around may still remember. But some names have disappeared who have been here for many years, some voices fell silent, and others - I think I fall into that group - have changed over the years and have become less enthusiastic in posting activity and disucssing things to death. We all become older, wiser, and a bit more "tired".
I still see controversies here and there, and I know with whom I will disagree over what - but I also see that these other guys no longer are as insisting as before, and I also see that me too does not feel the drive of wanting to nail down my point with all rigor anymore, too. So it goes. The long time members here know what I mean - for those who are relatively new, arriving within the last 2 years or so, it may appear to be a hot place at times. But believe me: it is nothing compared to the heat that has been there, years ago.
So take it as it is, and be happy with it. Not many forums I have seen on the web that could compare to subsim.