> exactly the fact that a reviewer had to develop a mental model

But do they? In my experience, at most workplaces it's simply a meat linter phase with the occasional useless comment about style (which should probably be handled by proper CI/CD).

Like if you don't even check out the code (generalized 'you'), then they can hardly build up that model. And even checked out, viewed in its proper context, Naur's famous paper comes to mind - the author who wrote it is the only one who has properly built the theory (which might have included alternative implementations that failed but have no visible artifact).

I'm not claiming that there are no places that go absolutely above and beyond with their review sessions, but I would argue it's really rare - and AIs are great at figuring out some of the context the PR description lacks.