I'm sure there were some delightful sex-positive spaces on Tumblr in the old days, but porn was a big problem on the service nonetheless. I've long run a blog on Tumblr about history and historical artifacts... Never had much interest in the world of Tumblr porn. But toward the end of the porn era, I was constantly being bombarded by DMs from porn bots and I'd say about a third of my new followers every week were sketchy porn bot accounts. It got to the point that I couldn't work on my blog during my downtime at work or when my kids were around because of the possibility that some explicit sex might pop up on the screen. It wasn't great.

I think something like the new system that Tumblr is proposing (adult stuff for those who actively opt in, walled off from those who don't) is the way to go, although managing that sounds tough.