The cool thing about many of these features is that I can push out some code that I can share with a hyperlink and other people can run it without installing anything other than a browser.
What you describe is a hack for lacking isolation/security/permissions/package management in the operating system. Seriously, if there was a sensible way of isolating apps and handling dependencies, it would be perfectly sensible to implement a lot of the current web "apps" as real applications.
What I was attempting to describe was a document format the freely mixes code, documentation, and interactive media. The present set of features in the browser allows for a very fluid mixing of these elements but the authoring tools and user experience are lacking in most browsers.
I can share similar documents via org-babel, iPython notebooks, or Matlab notebooks, etc... but each requires the user to be accustomed with those applications to install them, fetch my code from a URL, load it into their environment, etc. With the present browser ecosystem they can fetch everything as a single document and run the interactive examples and modify code on the fly... if they're willing to hop over the developer-tools wall.
What you describe is a hack for lacking isolation/security/permissions/package management in the operating system. Seriously, if there was a sensible way of isolating apps and handling dependencies, it would be perfectly sensible to implement a lot of the current web "apps" as real applications.