I thought 'stacking' PRs was useful in two circumstances.

1. The PRs are across different related repos, so they literally can't be combined into one PR.

2. You want to keep producing work while the first PR is in review. So you stack subsequent PRs onto the same branch. Basically just pipelining.

But this feature doesn't seem to hit either use case, and instead just seems to be a different form of stacking commits into a single PR. The standard advice has always been to make atomic and meaningful commits (using e.g. rebase to tell a nice story for the reviewer). And reviewers can go through commit by commit if they like.

What am I missing?