You haven't informed much to be honest. Whenever you're pressed for real bits of information, you just say you can't reveal the facts because they're secret and revealing them would help the spammers. So you're not doing much to reduce the uncertainty surrounding this topic which is critical to quality information. You're just generally claiming that the methods we're describing won't work while providing nothing but appeals to authority.

The information you've provided is the fact spammers try to obtain invitations and create aged accounts in order to look legitimate. This is already known and is the reason why you turn accounts and invitations into scarce resources to begin with. Spammers should not be able to just randomly create accounts, they should need to be invited. Whoever invites someone is vouching for them and responsible for their behavior. People should be inviting good people who they trust, not random spammers on the internet. You enforce this by also punishing the guys who invited bad people into the community.

I'm not claiming you're wrong either. I'm defending the rationale for the methods I've seen actual administrators employ to manage real communities. Those guys weren't up against spammers either, they faced far more serious adversaries.