> ChromeOS is the closest we have to the idea of "the browser should have been an OS", and frankly its a fucking terrifying idea.

I think the intended meaning of "OS" was more like "self-contained environment for executing code", rather than "single, user-facing shell on top of hardware drivers", i.e. think Smalltalk image rather than ChromeOS, Windows, Linux+GNU+Gnome, OSX, etc.