Agreeing with you, mini rant time:

Why in the fuck do desktop computers have user-based permission models? Don't answer that, I know why, it's because they inherited them from the server-OS ancestors, but it's retarded. Desktops are personal computers, there is no reason to stop the user from doing what they want because it is their computer. Some might say, "oh, well, we can protect the system from malicious software by limiting user access to it" and they're correct, but who gives a shit? If my OS gets destroyed I'll reinstall it. It's a bit of a pain, but whatever. What's really important to me are my documents, my work, and the user-permission model does jack and shit for protecting those as the ransomware wave proved.

Application-oriented permissions are the obvious and correct way to do things in personal computing.

There are desktop computers which are in shared environments (computer labs, public libraries, kiosks, teller lines, etc). So user-based permission models make a lot of sense for desktops.

Not really. There are better solutions than user permissions for those situations, we used them all the time in the 90s when multi-user didn't even exist in the Windows or Mac Desktop world.

Network resources, hosted on servers, need user permissions. Not desktops.

In those environments the same local user account is usually used. Or, a network account and in that case files are usually stored on a server.

Thanks for sharing that link with me.

Never heard of Sandstorm before. That's a really impressive product. I'll definitely be using it in the future.