There is an even worse consequence. If the “advanced flow” is managed by Google Play Services, under the current mechanism, scammers can simply tell their victims to disable Google Play Services. Consequently, Google could block the ability to disable their proprietary blobs under the pretext of “protecting users”.
“Sideloading” is obviously a ridiculous term made by Google. Is there anything called like this on Windows?
As many others here has already mentioned, this sort of thing really does still happen (and happens regularly in my country (Vietnam)). To be honest, I was a bit surprised by this question; is fraud really not a common occurrence where you live?