Tumblr has the resources and technical capability to detect and remove illegal content quickly, and the resources to identify adult content in general. I firmly believe that the issue is in monetizing the adult content, which Yahoo, Oath, and Verizon did not seem to want to do. By removing it, you don't have to host it anymore, and a greater proportion of your traffic is monetized.

>I firmly believe that the issue is in monetizing the adult content, which Yahoo, Oath, and Verizon did not seem to want to do

Working in the adult content space will get your business blacklisted from mainstream content. No one is going to have official relationships or work on exclusive deals for your platform if their content is going to be side by side with pornography, or even perceived to be alongside it.

Illegal content? I am under the impression that it was more about the advertiser unfriendly content.

There is more illegal content on pornhub then any other site.

Citation needed

See this thread: https://news.ycombinator.com/item?id=19819608

Isn't Pornhub filled to the brim with illegal content as it is?

by illegal, I believe the poster was mostly referring to child or violent content as opposed to copyright.

My understanding is that they and their subsidiaries actually own a lot of the content that you're probably thinking is "illegal" or "copyright infringing" [1]

[1] https://en.wikipedia.org/wiki/MindGeek

I've seen a lot of like "boutique" porn videos on PornHub that seem to have come from small-ish porn sites. Don't really know if PornHub owns the rights to those. Also, I've also seen some foreign porn flicks there and I also had my doubts about those.