[cubesnooper]

100% of the spam I’ve gotten over Signal in the past few years (two messages) has been from cryptocurrency scammers, exactly the sort of people who would have $5 in cryptocurrency many times over to create new accounts with.

[zrm]

Which is why rate limiting by phone numbers doesn't work against them either, as you've noticed. If they have $5 in assets to burn then they can buy a $5 prepaid SIM card.