Have you not heard of the internet? People could do all that long before Bitcoin's blockchain came online. I guarantee you people are not using the blockchain for the purpose of porn, when there's a much better medium to that sort of thing.
That's not true, man. People used to do that, but then the government got smart about it and that's why they banned megaupload and other file2sharing sites. I think I heard that piratebay got closed down too.
Point is, there's always a crackdown after a matter of time.
And it's even moreso if it's your personal info, like if someone has inappropriate pics of you and they post it online, you can get a court-order and it WILL be taken down.
Sure, people can re-upload to a new site.. but the point is, that new site will eventually be taken down.
But no one can enforce anything on the bitcoin blockchain, and that's why it's scary.