Dan Nosowitz hits the nail on the head in I Don’t Know How to Waste Time on the Internet Anymore:

And then, one day, I think in 2013, Twitter and Facebook were not really very fun anymore. And worse, the fun things they had supplanted were never coming back. Forums were depopulated; blogs were shut down. Twitter, one agent of their death, became completely worthless: a water-drop-torture feed of performative outrage, self-promotion, and discussion of Twitter itself. Facebook had become, well … you’ve been on Facebook.

Now it’s just ads and mediocre content marketing.