I love/use them very much, but we really should stop being so naive, it only takes a single bad apple..
At least that's what I used to hear all the time. We've now seen that was hogwash.
Linux will let you have the most locked down box in the world if you want.
Linux sandboxing scene is completely broken for end-user usage, it’s only good for CICD pipelines. If I want to open a file with a program, I don’t want to see an empty drive, neither do I want to kill the program - there should be a proper interaction between the user and the program, like mobile OSs do. Flatpak does have something like that, but only for files and not even that is seamless (plus flatpaks mix packaging with security for no good reason, imo).
You literally run basically everything as the same user, every document, family photo is saved, and thus available for r/w by any process, as those share the exact same privilege. This includes that npm install with millions of dependencies as well, that could literally install a screensharing malware with clear access to any internet site and you wouldn’t even notice.
The age-old xkcd is still true: the only thing secured is being able to install a video driver.
Or I just run it in docker and only mount what I want. No VM overhead since cgroups are native.
"I don't want to make that decision! I want total privacy!" - Great, use Tails which is a distro that goes all in on privacy.
Regarding AppArmor, how do you write a policy that would allow a text editor to open only files that user has chosen in Open dialog?
In this case we can say that Windows is also absolutely secure - you can just write a kernel driver that would protect sensitive data from applications.
Your distro already has AppArmor files for your distro software.
You can also kick it into learning mode if you desire.
You could also just stick to flatpaks/snaps - totally sandboxed.
You could choose Whonix where every app is an isolated VM.
Or choose tails where any egress is locked down and monitored.