It's not recommended because you can just use the --autosquash flag. No reason to make it the default.

especially since if you are rebasing you may want to rebase your changes from one branch to another (i.e. move to top of main or from on top of one feature to another).

So instead you can just do git rebase --autosquash -i last-good or just git rebase --autosquash and let it squash it down for you.