Most of the porn is illegal because it violates copyrights, the 10 times reencoded scenerips on PornTUBE are not exactly official.
Most places have no solicitation laws and other privacy laws that do make spam illegal.
You also neee to count in piracy and general violations of copyright laws; you'll be surprised just how much content on youTube is illegal search for "full movie" or "last week tonight full show" and you'll gea quite a few legitimate hits.
Like it or not from a logistical point of view illegal content makes up the bulk of the traffic, that said it isn't any different in any other field if we take global shipping then illegal arms and drugs probably make a nice chunk of global shipping (revenue wise) there also it doesn't mean we need halt all global and local logistics operations.
Illegal porn rips on aggregate sites are uploaded by the producer themselves, who are usually a sister company or subsidiary. This is done in a very nudge nudge wink wink manner to drive ad impressions and sell exclusive content
