If posters are not anon, you can use web of trust to filter spam (only show posts from friends of friends of friends of... for example)
but for anon posters, the only decentralized spam deterence that can work is pow
Discussion
i see, could spam bots not post on it, it just would take longer and the person making the bot would be forced to calculate if it's worth it. but lets say tao or something like it, had 10000 visitors looking, someone might(?)
you’ve got it exactly right, it adds a cost to the spammer. at 10,000 visitors spammers might spam the 21-23 difficulty, so everyone moves above that where it’s not worth it for them.
my only worry is ASICs which would have a asymmetric PoW advantage over normal posters. i’m hoping bitcoin mining ASICs don’t work for nostr