It works though. It turns out if you give people a platform a lot of them are willing to do free labor for little of value in return, just look at the explosion of games that rely on UGC like Roblox, or (as the author points out) Reddit. Even here we submit articles and get given points.

Why pay people when they're perfectly happy to work for (effectively) free?

I agree that it works, that's why there are so many popular communities. However, how much better it will be if people can actually pay their bills with this work?

Maybe participants receive value from code they consume freely, so they return value the same way.

Maybe these platforms will end up on peer-to-peer content-hash networks instead of "hub" and "stack" silos. Then the platforms won't retain much value. So I guess it's opportune to monetize them soon before that can happen.

Participants really receive value and I think this is why the model works. However, they don't receive the value they deserve...