Earlier quoted context omitted.
If they really want to go down this road, it feels like there's only one destination: real Know-Your-Customer-esque identity verification to prevent registration of duplicate accounts, like banks and X.509 CAs do. If-and-when they do that, they will finally have an actually-effective tool (in the form of being able to ban people "for good") to stop harassment. Until then, it will just go on forever.
Urbit comes with this kind of identity management baked-in. It hasn't been shown yet to scale to the proportions of reddit. I'm not sure that even reddit has enough staff now to do that.
Ideally: imagine that the government of each state/country—who already have to work out how to deduplicate people for purposes of taxation, Social Security, etc.—acts as an OAuth identity provider. Then doing KYC becomes as simple as having a signup process that requires an OAuth login, and having a whitelist of identity providers you'll accept for that login (presumably just government ones, but there might be interesting edge-cases.)
In other words, imagine a site that detects the country you're coming from, and presents a single button saying "Sign Up with [name of country] Federal IDPass" or something similar.
The first time you see one, you'll probably be forced to set up your Federal IDPass account, which will likely be a huge hassle (though I could see it being as easy as showing up at e.g. your local post office with your regular physical ID. A process similar to voter registration.) Every time after that, it's like logging in with Google or Facebook.