> PRs are the first time your reviewers have seen that change, so there is no opportunity downstream to do the things you're suggesting.

Yes, but I'm arguing for that it shouldn't be the first time they hear about that this change is planned and happening, and their input should have taken into account before the PR is even opened, either upfront/before or early in development. This eliminates so many of the typical PR reviews/comments.

Figure out where you are going before you start going there, instead of trying to course correct after people already walked places.