It's been a long time since I contributed much of anything, anywhere. A lot of it has to do a changing of the tides.
As you've mentioned, many of my old favorites are gone now, for one reason or another. Part of it has to do with simply getting older. Tastes change, obligations in real life start to weigh more heavily, and so on. But that still leaves us with old favorites vanishing left, right and center.
In their place, a new crop has sprung up. And I don't want to discourage anyone just because my personal tastes do not align with theirs. Yet that is precisely the reason I don't contribute to FB, the BEA, or to CYOTF these days. What I like just isn't there, or else I have to sift through dozens of episodes of drek (that being anything that fails to stir my interest) to find a single, probably poorly written episode which appeals.
I have nothing against these story branch "sagas". Epics, be they individual or collaborative efforts, are a mainstay of fiction in general. My aversion to those going on here at FB can be summed up more or less as follows.
Every chapter is nothing more than an excuse to lump more TF onto one character or another, treating TF as the sole motivating factor of the "story". The TF should, in my opinion, be incidental to or else facilitate the plot.
Poor quality. This is actually a very minor issue for me. I can overlook something written poorly if I can at least derive enough structure from the original post to fill in the blanks and make the corrections in my head on the fly. None of us, as far as I know, make a living off our skills as wordsmiths. That said, much of what I see is nothing more than "this TF happens to this person, which is probably a main character who's name is being misspelled, but might not be. Turn in next time to find out! Maybe." It grates upon the nerves.
And then there is the change in tastes I mentioned earlier. It isn't just old bastards like me. My tastes have changed, to be sure, but it seems to me that the newer crop of authors have completely different interests. Examples abound, but turning otherwise straight male characters into gay male characters is the one which strikes me the hardest. (yay, puns?) Diapers, gallons upon gallons of semen, and previously strong characters suddenly becoming submissive push-overs in the presence of ANYONE telling them what to do are further examples.
These things were always with us, to be sure. But these days, they seem to be the rules rather than the exceptions. Gone is the playfulness, the cartoonish episodic nature of plot-lines devoted to little more than an excuse to TF someone, or anything remotely resembling a plot-line in which the original character has a hope in hell of getting back to nearly normal again. Character death is all the rage these days.
The fact that I recognize the handles of less than 1 in 10 authors these days doesn't help at all. Weirdoid, for all that their kinks might not jive with my own, was at least a name I knew. I knew what to expect. I knew the quality of his work (and it WAS quality work!), and I had a fair degree of certainty that it would add to the branch and move things forward, even if there was no TF at all. It gave me something to work with, or just a good read if I wasn't up to continuing it myself.
But now? Not so much. Now days, most of the authors I recognize due only to the quantity of posts they churn out, most of which are brief, poorly structured, and contain exactly nothing of interest to me.
OP, you aren't alone. These emotions and observations have been pretty wide-spread, and spreading over the last ten years or so.
I wish I knew what, if anything, could be done about it, but I always feel like an old man yelling at kids to get off my lawn when I think about it too much.