[SulfurHexaFluri]

Browsers are way more complex than OSs these days. Mozillas Servo project had over 40,000 commits and still wasn't ready for production and it was only a small part of the browser. I don't think there is anything else that could have 40k commits and still be a tech demo.

[trhway]

back in 1999 looking at nspr (Netscape Portable Runtime - the foundation of Mozilla) i remember thinking - it just can be packaged alone as an OS, similar to Java OS (which i had been working with before that our Mozilla project).

There is also another aspect to it - one can imagine that the time of an OS which would run web apps as first class citizens (in the correctly engineered sandboxes/etc.) just hasn't come yet. In the meantime the browsers are just ugly stop-gap 0.x version of such an OS (there is a reason they are "browsers" as their roots (incl. deep architectural roots) are in browsing of static content, and everything else is bolt-ons - the integration of JavaScript engine for example back then could be best described exactly as a "bolt-on").