What is the advantage to this, other than maybe being easier to send over email?
To me, the important part is you have a logical "unit of change" that you're proposing to the codebase, whether that's a single commit or a branch or a jj bookmark or whatever seems more an artifact of the underlying transport layer (email or github or whatever) than any kind of intended functionality of the design.
- reverts are significantly easier
- bisect will work because the code is expected to code/run at every commit
- rebase becomes easier in the common case
- the transport does not matter, at all. Fully anonymous contributions are possible
- commit messages are easier to write because the changes are smaller and more focused
Several commits could encompass changes necessary to make a particular feature work (ie. patchset) but because each commit is self contained they can be reviewed and tested individually (in order, usually) instead of a one big diff. It's easier on the reviewer, though there's likely a bit more overhead.
It's not an ideal way to operate for most shops, but there's really no reason you can't have a PR/MR/changelist/whatever that is a single branch with X commits on it and you ask the reviewer to review each commit individually instead of as a whole unit (as GitHub and other forges usually expect you to).
That and don't let reviews pile up such that you have 5 dependent in-flight reviews, something else is wrong if that's happening.