the number of projects that require the scaling factor of something like this is very small. git with lfs scales very well for most repositories. That said the actual flow of git is pretty raw. There are other pretty solid projects out there that support undo commands into git.
Stacked PRs are a blessing and a curse - still not convinced they are the correct way to build software as a team.
Eh, it’s pretty hard to make a case that you don’t want stacked diff sometimes.
Obviously life is simpler if all your work is sufficiently non-intersecting that you can send separate diffs/PRs and e.g. rebase them separately, but if you have Big Feature X and you still want small, single thesis diffs, where else do you turn?
Public projects, sure. But plenty of companies have very large codebases that would benefit from this. Even if Git can handle it it can get very slow with largish repos.
Stacked PRs are a blessing and a curse - still not convinced they are the correct way to build software as a team.