Pardon if someone mentioned already.
Banning the porn altogether will and has killed the sight. No doubt about that. Many artist, sex workers, and the LGBT community have been negatively affected in ways Tumblr could never even concieve, so the social impact has deeper impact than anyone outside of Tumblr will ever even know.
BUT......
The reason this came to fruition was child porn, and beastialilty to a lesser extent. Both were rampant on Tumblr. So rampant you didn't even have to try to look for either to stumble across it. Many of Tumblrs users banned together in the final months to combat this, but like the Hydra, they would cut one head off, and several would regrow in it's place. So Tumblr had to use the heavy hand and put a blanket ban on all adult content.
So it is what it is. Tumblr signed it's on death warrant by banning adult content.
I've heard all the conspiracy theories about white supremacy and anti-LGBT etc nonsense, and that's exactly what it is. Nonsense