As you say..it can be regulated
It can't be regulated as you seem to think of regulated.
I don't know how to explain it.
Try this. Using Child porn as worst example.
Take PornHub, arguably the biggest porn site online. They're a business, they employ staff, there's a boss and it relies on ads to pay them. Someone decides what to feature and what to not feature. There is also a massive community of amateurs uploading their own videos.
Pornhub won't host CP because it would negatively.impact their business, advertiser's would pull out, profits would drop.
PornHub is curated by its staff.
Follow me so far?.
Porn hub is WHSmith. I know it's a hard image but stick with it.
PornHub as WHSmith is on the High street of the internet. Along with Amazon, Tesco Groceries etc. All porn sites run for profit are high street shops.
So in your mind picture a town with a high street, it has WHSmith or Pornhub, Waterstones, Amazon, Tesco etc etc.
Is that the only place.in a town you can buy things? Yes?.. no..
Down the pub there a bloke called Dave and he sells dodgy gear from his bad.
Aka "The Black Market"
Porn hub isn't available in the black market, they're a business and need to make money.
So we have Dave, selling dodgy gear in a pub. Cops can arrest Dave, but Terry is in the pub next door. Cops arrest Terry, nevermind, the Sunday carboot is tomorrow and there's plenty of stalls selling knocked of adidus and Nyke.
This black.market exists on the web as well. It's called the Dark Web. It's bigger than the high street and it exists in millions of computers around the world. There you can find Guns, CP, slaves etc etc.
And just like Dave, Terry, dodgy Carbooters, it's impossible to police because one Dave will be busted but hundreds upon thousands more will appear.
Does that make any sense?
This one block, any porn block, will affect the high street and just push buyers to Dave and the carboot..
Is that any clearer?