This is the kind of thing that the browser should not need to do. This is the kind of thing that the operating system should be doing. The operating system (the thing you use to run programs securely) should be securing you from bad anything, not just bad native applications.

A large part of the web is awful because of all the things browsers must do that the operating system should already be doing.

We have all tolerated stagnant operating systems for too long.

Plan 9's inherent per-process namespacing has made me angry at the people behind Windows, MacOS, and Linux. If something is a security feature and it's not an inherent part of how applications run, then you have to opt in, and that's not really good enough anymore. Security should be the default. It should be inherent, difficult to turn off for a layman, and it should be provided by the operating system. That's what the operating system is for: to run your programs securely.