Are DOM browsers the edge case?

I think the answer might be Yes.

You want your application to work on the web so you write it to output semantic HTML, if you do this without using script (or noscript tags) your site should work on pretty much any browser that understands HTML regardless of platform, OS, browser version etc... that's quite a lot of different user-agents running on, mobiles, iTV, games consols, PCs etc... A subset of these user-agents will understand javascript to some degree, and a sub-set of these will understand DOM. If you then think of DOM browsers as a edge case (albeit an improtant one) everything falls into place.