The ability to do this depends on the will of private hosting providers and ISPs. It’s the same problem. It’s infeasible to maintain a site that permits all legal speech. It’s a constant legal battle and you’d better know a great lawyer who believes in the cause enough to work pro bono.
For reference, Compuserve was an ISP that historically didn't moderate ony of its content on its forums, under the legal framework that not moderating anything meant Compuserve wasn't liable for any of its content, while another ISP Prodigy lost a defamation lawsuit because they did moderate their forum's content. This gave rise to the Communications Decency Act which allows these services to moderate some content without being civilly liable for all of the content on their service.
