I don't think this is it. The main driver is that several operations in GH are scoped around a PR, not a commit. So the reason you need stacked PRs is that the layer of tooling above `git` is designed to work on logical groups of commits called a PR.
Right, the argument against: "how is this any different than splitting into single commits?" is simply: In general you want just one level above a commit which is the PR
I don't think this is it. The main driver is that several operations in GH are scoped around a PR, not a commit. So the reason you need stacked PRs is that the layer of tooling above `git` is designed to work on logical groups of commits called a PR.
Right, the argument against: "how is this any different than splitting into single commits?" is simply: In general you want just one level above a commit which is the PR
One of the advertised features of this is being able to merge all the PRs at once. Which would also be the case for multiple commits in a single PR.
That's possible but not mandatory. In the current UX you can only approve/submit all or none.