I think people don't upvote the NSFW posts because they don't want to be considered creepy. Or they access steemit at work and don't need a meeting with HR on their record

Or, the spam porn posts drown out the people making original content and nobody wants to wade through the spam. It kinda makes accounts like @pornbooster necessary.

Artistic nude or homemade porn should be welcome as long as it's marked NSFW. I'll upvote the minnows fighting the good fight.