I had a plan involving opentimestamping identities and requiring them to be old, but it is broken because one could timestamp thousands at once, so I wanted them to be timestamped in relation with others, but that just does the reputation game again, so I'm not sure it makes sense.

the other idea is to do fidelity bonds and their variations, like joinmarket used to.

but honestly I think the paid nostr.wine relay is pretty good, I'm just sad that I couldn't find any other relays that operate in a similar vein (single steep upfront fee)