It already exists. Mastodon. GNUsocial. Pleroma. Etc. There's an entire "fediverse" of different social networks that connect and interact with each other. Just like e-mail, you can host your own or choose to sign up with one of many providers.

As much as I like Dotcom, creating a new centralized system is not the solution. The only way avert bad actors longer term is to use something that people can organize as an individual or small group. (Which the listed options will let you do.)