Mass reporting means spending huge amount of reputation which doesn't really invalidate reputation of people who still certify that the person exists.

The problem with the current systems is that reputation buying is not transparent. In my system, it would be a public record, who endorsed who. So you could go back and track the fake reputation.

Also real people have some TTL with their accounts. Unlike links, "I am real person" is not nearly as fungible.

Exactly, the 'social graph' is also a huge source of cancel culture.