You might not be able to make your web app with zero, but chances are it needs a lot less.
Look at Old Reddit for example; it used Javascript for inline comment reply textboxes and for expanding sections of the tree. With it turned off, everything else still worked. Of course, that's gone now.
Do you really need three megabytes of JS to replace the whole page with the video player when I click on a video, or is <a href="/video/foo"> enough?