[snoot]

Clearly not true. A lot of spyware and malware masquerades as legitimate software.

[gambiting]

And literally none of it would be allowed on the app store, just like it isn't now. Again, it would change absolutely nothing. Scammers would sooner convince his 80+ year old mother to tell them her bank details than they would walk her through the process of installing a dodgy app through sideloading.