I think we're going to have to make some choices.
A completely anonymous stranger has no way to prove that they're human that can't be imitated by an AI. We've even seen that, in some cases, AIs can look more human to humans than real humans do.
The only solution I can think of to that problem is some sort of provenance system. Even before AI, if some random person told me a thing, I'd ignore them; If my most trusted friend told me something, I'd believe them.
We're going to need a digital equivalent. If I see a post/article/comment I need my tech to automatically check the author and rank it based on their position in my trust network. I don't necessarily need to know their identity, but I do need to know their identity relative to me.
Reputation tracking is the key. The most simple option is open-invite invite-only spaces: Any user can invite more users, but only users with an invite can participate. Most Discord servers work like this, secret societies like the Oddfellows do, as does the other site.
If you keep track of the invite tree, you can "prune" it as needed to reduce moderation load: low quality users don't tend to be the source of high-quality users, and in the cases where they are, those high quality users tend find other people willing to vouch for them faster than their inviter catches a ban.