Aspects of this already exist to varying degrees of polish. Conduct a search for pleroma, mastodon, gnu social, hubzilla, friendica, diaspora, etc. and you'll see a diverse ecosystem of platforms. By the way, this ecosystem is referred to as the fediverse (federated universe). Sure, the thousands (yes thousands!) of mastodon servers/instances receive most of the limelight, but mastodon is not the only platform. The old challenge used to be the network effect ("oh, but none of my friends are on network X...")...but with recent stats citing over 2.5 million users active on the above networks...it is just a matter of time when one of your friends will make their way onto the fediverse, pulling you and your other friends into it. So - perhaps a little prematurely - I welcome you to the Fediverse! :-)

there's activitypub.. it's a federated social networking protocol. the most prominent implementation is mastodon (joinmastodon.org). Counting almost 2 million users by now

Would you find an issue with user interaction though? If you provide a means of customization, then your site’s aesthetic depends upon a user’s incentive to change their page’s display. Once a certain fraction of ppl stop caring, then you’d see a visual degradation of the site that would cause a ripple effect.

A decentralized social network protocol is needed (ActivityPub is something like this), data stored in a neutral way, and the software. When exchanging data between users, you exchange only data, and you see it based on your software (protocol implementation).

The software would ideally be hosted on the cloud, so it's always online. You log in your software and see all your updates/interact with others.

That’s an interesting idea but creating decentralised social networks seems quite hard. IMHO it’s easier to just use regular web sites running e.g. Wordpress, Discourse or SMF[0].

[0] http://simplemachines.org/

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.

Agreed. We need a common social media specification. Like Diaspora, but just the spec. Diaspora is a solution, and solutions would implement the spec. Then sites like Facebook/Neocities/Wordpress could comply with the spec. How you treat your own posts on your own site, with your own theme etc would be up to you. Your feed would exist within your own website and would consist of posts pulled in via RSS or some other syndication spec.