> One thing that's weirdly precarious is how we still have one big environment for personal computing and how it enables most malware.

You're not the only one to note the dangers of an open-by-default single-namespace execution model. Yet every time someone proposes departing from it, he generates resistance from people who've spent their whole careers with every program having unbridled access to $HOME. Even lightweight (and inadequate) sandboxing of the sort Flatpak and Snap do gets turned off the instant someone thinks it's causing a problem.

On mobile, we're had containerized apps and they've worked fine forever. The mobile ecosystem is more secure and has a better compatibility story than any desktop. Maybe, after the current old guard retires, we'll be able to replace desktop OSes with mobile ones.