Why does `pull.rebase` default to `false`?

This is more of a question of practicality. Literally all of the team and project workflows I've experienced have demanded that `git pull` actually perform a rebase of your local commits, as opposed to introducing a merge commit. This means setting `pull.rebase` to `true`. I can't think of a practical, day-to-day use case for wanting merge commits after a pull. Since the subject commits of the rebase are always local, there's no harm to anything upstream since they haven't been pushed yet.

I'm sure there are edge cases that explain why the default is `false`, but I'd argue that it is likely a case of the minority concerns becoming an inconvenience for the majority of users.

Thanks in advance for any enlightenment!