Where did I claim it's the only thing needed to stop a person like that?

You gotta start somewhere. This is a nice and easy way to do that's completely within the reach of the tech community. There are no laws requiring that, just a sign of a good will.

If it were up to me, Cloudflare would block at least 30 other websites, starting with Gab. Unfortunately, it takes a shooting or two for them to realize that they have a problem with a client of theirs.