I get the spirit of this project is to increase safety, but if the above social contract actually becomes prevalent this seems like a net loss. It establishes an exploitable path for supply-chain attacks: attacker "proves" themselves trustworthy on any project by behaving in an entirely helpful and innocuous manner, then leverages that to gain trust in target project (possibly through multiple intermediary projects). If this sort of cross project trust ever becomes automated then any account that was ever trusted anywhere suddenly becomes an attractive target for account takeover attacks. I think a pure distrust list would be a much safer place to start.
Thing is, this system isn't supposed to be perfect. It is supposed to be better, while worth the hassle.
I doubt I'll get vouched anywhere (tho IMO it depends on context), but I firmly believe humanity (including me) will benefit from this system. And if you aren't a bad actor with bad intentions, I believe you will, too.
Only side effect is genuine contributors who aren't popular / in the know need to put in a little bit more effort. But again, that is part of worth the hassle. I'll take it for granted.