That's wrong. You can clear both cache and data of a system app on a typical Android device. You just can't uninstall it. The base .apk is stored on a read-onl

That's wrong. You can clear both cache and data of a system app on a typical Android device. You just can't uninstall it. The base .apk is stored on a read-only system partition, so you can't completely get rid of it, but typically you should be able to remove all data of that app, clear its cache, uninstall any updates it downloaded (since those are stored on another partition), and also disable it. I haven't used any OS by Xiaomi in a while, so I don't know if they changed anything about that. Though I used to run their MIUI OS on my Samsung Galaxy (S2 or S5, I don't remember) for a while. That one was the opposite of locked down and even shipped pre-rooted, but it's been a long time.