> A lot of criticism for not being a "real" OS from a technical perspective
It's not criticism, an actual full operating system written in NW.js would just be very special in its own way.
NW.js requires an underlying operating system to function, so if it really could be called an "NW.js-based operating system", there would have to be interesting things like bootstrapping WebKit as early as possible and then doing everything else in there.
And that would also have stark performance implications. If core-libraries were written in NW.js, getting something as fluid as in the videos, would be absolutely incredible.