Alan Kay reckons they aren't OS:es enough
https://www.quora.com/Should-web-browsers-have-stuck-to-bein...
Edit: I removed some stuff I first wrote.
> It’s both surprisingly and dismayingly difficult to get people — especially computerists — to criticize the web and the web browsers — even more so perhaps today.
Definitely agree with this. People tend to view it as something handed down to them by Gods. It's not.
Edit 2: This needs a larger discussion. I just posted it as a new submission.