Because the people who sell Cheerios and Volvo's do not want people posting pics of their ads in some camgirl site and annoying the larger audience who don't (admit to) watch porn. Head on over to pornhub, marvel at what must be absolutely mammoth page view counts, and then wonder at the below-the-bottom-of-the-barrel ads that the site is filled with.

I eat cheerios. I wouldn't not eat cheerio's just because I saw that bee next to a gangbang...

I think the disconnect here is that advertising has a tacit endorsement of the site, everyone knows Volvo and General Foods is writing a check to the pornography host to display their ads.

Brands were so freaked out to have their dish detergent show up next to an ISIS video because whoever uploaded the video gets their check for $5 or whatever, and then they're literally supporting terrorism.

The world is nothing like ad-hungry. Ad rates are falling to the floor.

Advertisers in the current environment can be as picky as they want to be.