I take a little time out of my day each week to browse "Show New" and offer some constructive feedback. I wish others would do the same, but c’est la vie.
As for your idea there have been a few attempts at this in the past, usually in smaller more intimate settings. I’m part of a private Discord with only about a dozen other devs who do exactly this, but we all know each other, so there’s a camaraderie that encourages everyone to share and give feedback.
The Discord example you mentioned is interesting though. A lot of the good feedback exchanges I've seen seem to happen in small private groups where people know each other, like friend groups.
The thing I'm trying to figure out is whether something like that dynamic can work with strangers if the incentives are structured correctly. My small experiment pairing devs up seemed promising, but it's obviously a tiny sample size.
I myself browse through new reddit posts to check out new projects and give them feedback to, and used this account to share this project and spark a discussion, though it is fair that it seems ironic with a single karma on my side.