Well, if you're reading this, you probably already know the answer. A better question might be, "Why are you still here?" Heh.
(My answer: Because I'm as stubburn as a mule and also lazy.)
Last week, Slate posted an article/interview about a study that analyzed the migration patterns of various fandom platforms over the last 20+ years:
Why did fans leave LiveJournal, and where will they go after Tumblr? I found it fairly interesting, although I'm slightly skeptical about much of the study's methodology. (To me, 1,866 survey partipants recruited via Tumblr doesn't sound like a representative sample, and there's no apparent breakdown by age, which I think would have been extrememly insightful.)
(ETA: I now realize I typo'd "participants" into "partipants" but it made me LOL too much to correct it. :D)
Here's the bit I found most informative, a graph from the study that summarizes platform usage over time:
One of the main points they made was that the biggest exodus from LJ (in 2012) actually happened a few years AFTER they'd pissed everybody off (in 2008), in theory because LJ users didn't really have an alternate platform to go to at the time. (Unfortunately, there was no discussion of the notable, albeit not overwhelming, increase in Dreamwidth users.)
And so, that's their explanation for why Tumblr and AO3 took off, because they finally offered viable fandom alternatives (Tumblr for the social, AO3 for the archive). Which, duh.
Actually, I'm mostly surprised by the fact that LJ has stayed relatively steady since 2014, although the author says that can be attributed to differing interpretations by respondents for what could be considered "active" participation (which, IMO obviously should have been something that was standardized -- like I said, some of the methodology seems sloppy).
I did like the study's conclusion, which basically seems to be, "People are slowly realizing that Tumblr isn't all that it was cracked up to be." Which is what I've been saying for about 3 years now. But the fact that the biggest question, "Where will everyone go from here?" remains unanswered is scary. I've watched the Oz fandom get smaller and smaller with each passing year as its members don't seem to be going anywhere else, they just go. And I wonder if other fandoms will likewise experience not so much fragmentation (as bad as that is), but downright disappearance. :(