Yes, that's the example I had in mind.

> you can uninstall it anytime

I'm sure it tells you that... but did you actually try?

The "uninstall" button is a lie: You cannot remove the app, you can only roll it back to some mandatory minimum version.

> Do you want to uninstall all updates to this Android System app?

If you "uninstall", the app still exists, and your only choice is to surrender and update it again. So yes, that "system app" is (as far as Google is concerned) absolutely "mandatory" on my phone.