I've always thought the "strict invitation trees" or vouch trees would be an interesting way to moderate a community, even before the LLM era. A user can vouch for an unlimited number of new accounts, but if more than 10% of the vouched accounts are banned or flagged down the line, the parent voucher acct is also banned/flagged.

Since it creates a tree structure, you can wipe out entire armies of bot/spam/otherwise accounts by following the vouches up the tree.