For example, you can submit PRs to non-main branches. Which means you can submit PRs to PR branches. Which should mean that a code-review asking for changes can just...be the changes.

This would work fine, but there's no UI for it in Github, so doing it is useless - no one wants to understand it.

And then if we had this capability, then realistically, shouldn't the comment UI work the same way? I can already checkout a PR as a branch, so why can't I just inline edit those files with comments and have them upload as comments directly? This would be much more effective since viewing the whole context of a change, rather then whatever git patch decides is the context, is usually necessary to properly appreciate a change.

Again: the functionality doesn't exist (and it's not technically difficult to implement) - but because of that, far too many reviews are just of whatever the change displays as in the UI.

Instead we have this miserable land of self-flagellation - "could you change X to Y?" - style comments, where the original author is needlessly put through extra actions to implement the change, re-push the branch etc. All things which have nothing to do with whether the request is a good idea.

There are actually dozens of great code review tools out there: https://medium.com/codeapprove/the-best-modern-code-review-t...

Im my opinion very few professional dev teams should settle for GitHub's default UI!