The issue is that you can't interact between profiles, or if you interact it's centralized. Looks like there is existing a decentralized social networking protocol: ActivityPub, having the features of social media (as mentioned in related comments).

There exist various attempts at decentralized social networks. But when I googled to find an up-to-date list I find they're all unfamiliar to me. All the ones I heard of previously are apparently dead or zombies now.

Decentralized social networks can't or won't do the kinds of orchestration of social interaction that help lubricate getting a social network up to speed. Many of those mechanisms, like bots, are underhanded and exactly what people want to get away from in decentralized networks.

We likely have to live with the fact that social networks are artificial creations, and that they are hostile to many kinds of expression. They probably can and should be better at preventing propaganda manipulation by hostile national adversaries, and at protecting the vulnerable from bullying.

But they're never going to be a force for good. Just a less-damaging vice.