Really, this is a bit too much IMO. So there are a few threads where idiots keep fighting about nothing. Close them, or even better, ignore them.
This is a free board. If people decide to invade this forum and post nonsense, they can do so. If you can't deal with that, you will be in trouble.
And there's always the option to create a new messageboard and only invite people that you know and like to post there.
And yes, when today's players retire, their fans might want to come here and post about them. Which is a good thing.
Think about it: when there are always the same people here, posting about the same retired players, won't you run out of material to talk about? Maybe that's why "other posters who share our exasperation contribute less and less as well", as Andy T said.
I really appreciate the work you have put into this forum, thanks a lot for that. But you just can't expect it to stay the same over many years, especially considering that the board gets busier every day. And there are ways to deal with troublemakers, there is no reason to give up everything just because of them.