I feel like that requires a lot of coordination that I, in the midst of development, don't necessarily have. Taking my WIP and trying to build a story around it at each step requires a lot of additional effort, but I can see how that would be useful for the reviewer.
We can agree that we don't need those additional steps once the PR is merged, though, right?
I have literally never met a developer who does this (including myself). 99% of all PRs I have ever created or reviewed consist of a single commit that "does the thing" and N commits that fix issues with/debug failure modes of the initial commit.
You never design a solution which needs multiple architectural components which _support_ the feature? I do, and would make little sense to merge them as separate PRs most of the time as that would mean sometimes tests written on the inappropriate level, also a lot more coordination and needs a lot more elaborate description then just explain how the set of components work in tandem to provide the user value.
We can agree that we don't need those additional steps once the PR is merged, though, right?