It's not the only solution but it might reduce PRs by a decent amount I would think.
If you see a PR and the guy is verified, you can check his name, his linkedin and where he works, at least there is some accountability if he introduces malicious code.
If the goal is to reduce slop, define slop. As a maintainer of a project you should be able to tell if something is slop.
If you don't have time to read PRs (which is the real issue here) that's fine too.
My guess is they want to reduce the amount of PRs, and ensure that the quality of the PRs passes an extremely high bar.