[faho]

Okay, now do emacs! Depending on build-time options, that can open text files, images, pdfs, archives (zip et al).

In fact I'm struggling to think of a single file type that truly won't have a use in emacs.

(It might actually make more sense to forbid editting executable files than going via type)

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>There's a lot more nuance in existing systems (SELinux) and potential future systems than just "allow everything or nothing".

The problem isn't that there isn't a lot of "nuance" in these systems, the problem is that there is!

Sure, SELinux will work if you have a static system or an SELinux expert under the desk.

Creating a system that works and remains understandable is much harder.