You can always force-push a cleaned up version of your branch when you are ready for review, or start a new one and delete the WIP one.
I hate (and fear) force-pushing and "cleaning up" git history as much as other people dislike squash-merging =)
It just feels wrong to force push, destroying stuff that used to be there.
And I don't have the time or energy to bisect through my shitty PR commits and combine them into something clean looking - I can just squash instead.
You can, but instead you can also just squash merge in one click. And avoid that people merge there dozens of fixes if you allow anything but squash merge.