Long debates on this matter, you are right on the spot of course for everything. I for instances have no problems with art showing nudity, however I've come acrossed with some postings here on DA that are clearly porn, that surprised me, "DA turned into a chat of porn meetings"
I can only say that parents should be more aware of what they're children are watching, things can turn wrong even here, teaching them from young age that the ways of the world are what they are... DA too should be more aware of the postings.