This. I am somewhat surprised allowlist isn't a thing. I get that there are times, you want to be open to the world ( say you are actually waiting for an interview call ), but this would easily solve a good portion of the issues. Am I missing something?

As long as you hardly ever meet new people, of course. Obviously this is not a trivial problem to solve, otherwise spam wouldn’t exist.

or they can create a new account on the same platform. but that's why i don't like platforms that force me to use my phonenumber as a public ID. because already today, if i block you on whatsapp you can find me on signal because my number is the same. so really the interoperability doesn't make it worse than it already is.