Everything I've ever read indicates that the widespread and ready availability of porn serves as excellent sex education. It is considered to be responsible for the end of the "That's not my bellybutton!" type joke levels of lack of basic knowledge of how sex even works at all. Its availability also has been shown to reduce the incidence of sexual assault.

There are certainly downsides. For example, it can lead to various unrealistic expectations concerning looks and predilections of a partner.

But my understanding of life, the universe and everything is that porn serves to fill a much needed role in basic sex education that we have yet to find another way to fill. Furthermore, comments here suggest that bringing back NSFW Tumblr will be different from actual commercial porn. The manner in which it is likely to be different is likely to be a positive antidote to some of the problems porn does have.

NSFW Tumblr is likely to be ordinary people expressing themselves without looking or acting like porn stars. It is much more likely to provide realistic expectations for what a partner is likely to look like, as well as serve as a space for personal exploration for sexual expression.