Oh no no no. If you are handling something as important as the Linux kernel, you will absolutely want traceability over anything as trivial as clean history. You will impose signed commits and signed merges only... none of these FF stuff. If you want clean history on top of that, you will enforce that on original pull request not after the fact.

I'm responding to, "there's nothing wrong with not having it clean."

Yes, there often is. And I do enforce it on the original pull request.

You need that level of traceability on each commit specially on the Linux kernel, all our little projects sure, destroy the history, is fine.