We already have practices about keeping PRs small so one could argue having to focus on crafting good individual commits is not that important in the grand scope of things. Especially if those carefully crafted messages will go lost after a merge. Some PRs require heavy reviews, while others just require a quick look through. From my experience people usually look at the changes and not the commit messages (myself including).
> Another feature of multi-commit development is when you notice that e.g. a particular feature won't fit in the next release, and you take only these changes to a different branch.
If your PRs are small you could also just move the changes yourself manually. Or you could do as you say and move each 'WIP' commit if necessary.
If you, in your very fast-paced environment, ever do code reviews, you likely noticed that showing the thought process, or separation of concerns, in separate commits helps reviewers wrap their heads around your changes. Adding commits that address feedback also helps the review process. Another feature of multi-commit development is when you notice that e.g. a particular feature won't fit in the next release, and you take only these changes to a different branch.