I only see two outcomes for this problem : an internet of verified identities (start by uploading your ID card). Or a paid internet, where it doesn't matter who you are, but since you're going to pay for that email or that reddit account, the probability that it's AI spam is greatly reduced. And i'm looking forward to none of them.
Members only comment blogs. Where you need an invite to comment also solves the problem. You need to know a real human to get access.
Bittorrent trackers, as absolute retarded as they are, have performed this experiment for us and the lesson we're supposed to learn is that this does not work. Someone, somewhere, has an incentive to invite the wrong sort eventually, which because of the social network graph math stuff, eventually means "soon". Once that happens, that bot will invite 10 trillion other bots.