People rightly criticize all of the problems around vendor-lock-in and rent-seeking with platform app stores, but this is a good example that they do indeed provide some value in terms of filtering out malware.

The degree to which they are successful at that and add enough value to overcome the downsides is an open question. But it's clear that in a world where everyone is running hundreds of pieces of software that have auto-update functionality built in and unfettered access to CPU power and the Internet, uncontrolled app stores a honeypot for malicious actors.