Playstore is a walled garden. And this article is a wolf cry exactly against malware from Playstore. In the end same social engineer techniques employed to trick people to install malware directly (see Windows) can be employed to trick the walled garden gatekeepers to allow malware there.

I would argue that having walled garden is actually worse. Once malware is inside can wreck havoc far greater than the open system of Windows. Sure, you get fewer bad actors inside but those who do manage to get inside will be fully free because of the false security its users feel.