Fans on Tumblr (and I think Twitter) will viciously harass anyone who makes "bad" representation of queer folks (and other marginalized group) while either leaving alone or only sending a fraction of the hate to folks who make exclusively straight (white, etc) stuff.

And for these people, porn or anything remotely sexual is automatically bad representation.

So I think a lot of people just gave up on posting yaoi online for fear of social media witch hunts.