I needed an official response from an administrator for updates
junkyard76 replied at 2019-05-31 02:58:01
It might not be important for you but it is for others.
And it's just one single variable ticked on, so no effort or costs needed. They're just deliberately withholding this feature from some phones.
And I guess that's the point that's the most salty. Why some Xiaomi devices have this and others not - there even seems to be a difference between China and Global ROM on the same device. what makes this really look arbitrary.