I think its hillarious that you gripe about a paid service when #nostr has paid private relays. If you want to filter out spam you are forced to pay a subscription fee to these paid relays.
By putting up a paywall orangepillapp (npub1ve8…9ka6) has filtered out virtually all spammers/scammers. I think they may have had 1 guy that kept trying to pay to scam and eventually gave up after being removed several times.