Commits aren't necessarily messy, but they're also not supposed to be necessarily clean. There's clearly two different work flows here.

It seems some people treat every commit like it's its own little tidy PR, when others do not. For me, a commit is a place to save my WIP when I'm context switching, or to create a save point when I know my code works so that I can revert back to that if something goes awry during refactoring, it's a step on the way to completing my task. The PR is the final product to be reviewed, it's where you get the explanation. The commits are imperfect steps along the way.

For others, every commit is the equivalent of a PR. To me that doesn't make a lot of sense - now the PR isn't an (ideal world) atomic update leading to a single goal, it's a digest of changes, some of which require paragraphs of explanation to understand the reasoning behind. What happens if you realize that your last commit was the incorrect approach? Are you constantly rebasing? Is that the reader's problem? Sure, that happens with PRs as well, but again, that's the difference in process - raising a PR requires a much higher standard of completion than a commit.