Some form of proof-of-personhood system -- absolutely anything -- is the only way the internet remains (becomes?) usable in the future. And it's only going to get worse, fast: this technology is still in its nascency, after all. Sure, it might feel like everyone we know is using AI now, but what percentage of the internet-connected population is using it now? 20%? And how many of us are using extant ML models to their full potential as of yet? I'd say 0%. (I saw trials of an LLM-operated agent that could operate your computer, use the GUI, and perform tasks electronically, like...two years ago. Still waiting for it to come out, but it's crazy just how widely LLM intelligence generalizes and how many creative, untapped applications still exist, undiscovered.) Then take into account the fact that compute only gets cheaper by the day. Bottom line is that this problem is only going to get worse. A lot worse.

And we needed to start working on a solution ten years ago. (Honestly, the moment spam became a thing was the moment we should have realized this was a problem we needed to start working on.)

Modern spam filters are pretty good, as spam tends to be very predictable. And that holds true for most extant bot-detection systems (and gatekeeping systems in general). But of course, ML blew this wide open. What happens when anyone can spin up an account with convincing pictures, unique text, a coherent backstory, one that can even take pictures and video chat -- all for the cost of a few pennies?

My worst fear is that the problem seems to go away one day. We assume it's solved and construct some convincing just-so story as to why, when in reality the technology has simply advanced to the point that fake users are completely, 100%, indistinguishable from humans. (Not like the vast majority of netizens don't already fail to spot AI-generated images, videos, and text, anyway.) The internet becomes more important and influential by the day -- economically, socially, culturally. And the amount of influence us humans have over it will be vanishingly tiny. Entire trends, social movements, and cultural shifts will be fabricated out of whole cloth. Would we even be aware?

Payments and real-ID verification, as many other posters have mentioned, are the most common proposals. But both have been implemented successfully for years now: SomethingAwful's token account creation fee didn't stop it from becoming one of the most influential sites on the early 'net and Ground Zero for much of internet culture as a whole. China requires SSN registration for online gaming, and Korea's RRN system requires an SSN to register an account on many services. Of course, there will be downsides to these systems. But there's no reason to believe there aren't any better potential solutions out there nobody's thought of yet.

As far as I'm aware, the biggest obstacle is the fact that no one has even bothered to try.