[jonathanstrange]

That solves almost no problem. Libel and slander will continue to affect you, there will continue to be toxic communities who instigate violence and violate local laws, and the feature encourages echo chambers and fragmentation. The worst system is when other people can see comments to your posts that you cannot see when you've blocked the commenter. It's the best system for smear campaigns and targeted character assassination. You'll never get a job and everybody hates you, and you'll have have no idea why.