The Gemini protocol is an interesting re-imagining of Gopher: extremely simple text-only content, with client-side styling. Identification via client-side certs.

I’m sure you could write a Reddit client that emulates this. For better or worse, it’s the most like Usenet today.

The most important difference a Usenet-like clients brings is per-message read/unread status, which is what enables long-running threads and discussions. Without most clients (most users) supporting such read/unread tracking, you won’t have long-running discussions, which changes the whole character of the medium.

Per-message read/unread status in practice requires keyboard navigation (or as an inferior alternative, paging with read/unread tracking like in web forums), which doesn’t work for mobile.

The lack of read/unread tracking is also why we don’t have long-running discussions on HN.

The only remaining medium with per-message read/unread tracking we currently have is mailing lists.

Not to mention kill files, allowing you to filter out people/topics/threads you don't wish to read.

Reddit Enhancement Suite is a sort of swiss army knife killfile. Sadly I don't think it is long for this world of New Reddit.

That's not true. Everyone had a voice on Usenet. The same cannot be said for Reddit unfortunately.

Some kind of social media protocol, that broadcast your posts to those that are granted to receive it. Perhaps it is not possible.

Usenet isn't threaded. That's just something constructed client side.

That makes little sense to me. Each post contains a pointer to its parent post in the thread. That's how the client side can construct the thread.