Because censorship is never abused
Let's watch municipal networks in Alabama block stuff critical of Trump, or those in California block Trump's tweets, and see how people feel about it then?
If we had net neutrality regulations (and made sure there wasn't a loophole exempting municipal broadband) then we wouldn't have to worry about stuff like this. If people are burning through too much bandwidth surfing porn, force the heavy users to pay for a bigger cap.
Though I suspect it will be people who stream all their TV that are the heavy users these days, most people don't have the stamina to surf porn for as many hours a day as they can watch Netflix :)
Biting the hand that feeds IT
