Interesting spelling, there. Vigilanteism. Hmm.
And the 3 billion people on the internet are asking how to stop online harassment? That’s clearly not the case, but that’s what your second sentence states.
It’s going to be damn hard to “police” the internet when said policing does not involve actual crimes that are on the books. It’s going to come down to opinions, agendas, and gray areas. And people are going to abuse it.
A self reporting model can easily be hijacked by those with numbers and a motive.
The internet is free speech. That’s how it has been, and should be. Having a moderator ban someone in an AOL chat room for being awful is perfectly reasonable. But even if they did sever this persons internet access — something you implied — that same person could call up any other number of services and connect with them.
When we’re looking at bad behavior that is outside of stuff that’s actually illegal, you’re getting into a politically charged and potentially highly dangerous space for free speech. Free speech on the internet means trolling. It means shitposting. It means unsolicited offers of sex. It means inappropriate questions.
If you’re not OK with that, fine. Don’t go where those things occur.