What happened was people ended up putting a lot of money and sensitive data on their computers and desired a system which wouldn’t expose that just because they ran the wrong software.
I should be able to run a crypto wallet I downloaded from a Kim Jong Un fan site while high and it shouldn’t be able to do anything I don’t give it permission to do.
It’s totally possible. Tabs in a web browser are basically this.
I can do it with VMs but that’s lots of extra steps.
The only place it seems to fall flat is network I/O - LAN access requires permission, but dialing out to the wider Internet does not.
Compare Windows, which has jack (except for bloated anti-malware hooks in NTFS.)
Linux is _trying_ to replicate macOS with Flatpak/XDG portals, but those still need more time in the oven.
Source: I use both a MacBook and a Linux desktop daily.
No it isn't, and no it doesn't.
And it is quite demonstrable that Windows can function without Secure Boot.
95% of people don't know what "Run your own software" means, because to them, the app store lets them chose what apps to install. And they don't get viruses and malware like their 2008 laptop did.
That being said, there absolutely needs to be a mechanism for "lowering the gates" if the user wants full control of the device they own.