>If that were true, the optimal solution is PRs with individual commits that all pass testing. I find it much easier to review a series of small changes for logical correctness than mashing them together into a single PR.

This is too myopic and explains how you can end up with good code, but bad architecture. A good review ensures both.

I like my PRs to be about high level goals, and I want them made of lots of commits I can review. The commits themselves can be the result of re-basing (which is fine within feature branches) and maybe not truly chronological.