Trolling is free speech, being a jerk is free speech, hate speech is free speech, pornography is free speech. Any forum that sets the bar at "free speech" is going to be filled with the dregs with depressing speed. There's a reason why Gab never really gained serious traction.
Another concept is just following a set of moderators.
Either way there is already Secure Scuttlebutt.
Distributed social media might solve this problem, but to be honest I don’t know a single person in my life on one. And I’d never heard of Secure Scuttlebutt before.
Fundamentally you still have the choice of curating some content or not. On the extreme ends are things like hate speech and exploitive content. Then there are “false” or incorrect information. You either allow them unchecked or you don’t. This isn’t a technological problem.
Outright ban all user tracking and profiling transparently with annual code audits and watchdog groups that can punish those in charge for not adhering to this, no advertisements, no selling data, and put 18f on the job of designing/developing it based off sound human principles, no army of behavioral researchers and Psychologists A/B testing bait-and-click engagement dark pattern metrics that penetrate deeply into the reward system of our neuroplastic brains and yanks on that lever of addiction formation with ease. Cut the bullshit and I'm on board. I'll even work for free on this if you promise to make it a reality, hell consider it a public utility if you have to so it stays funded and maintained.
The Advertising industry needs to be lobotomized and severely scaled back to more traditional forms of reaching people where they are, not vacuuming up every ounce of data their movement, click, search, and vitals generate unbeknownst to them. Good riddance.