I used to agree, but now I actually think there are two webs. There is the original web, the document web, but there is also the application web. Sometimes the two overlap, and almost every site has at least some documents that should be plain ol' HTML.
However in working on the application web for the last 5 years I've come to appreciate the power of new approaches for web-based user applications. It turns out that generating full HTML pages for users can turn into an incredible waste of resources and significantly worse UX, for what amounts to a very tiny accessibility and SEO advantage. Facebook is the canonical example here. The way they load a page is brilliant from a UX and server resource perspective.
But consider apps that are much less dynamic. Say you have a 50k page with 1k of dynamic content per user or some other variable such as country. Page caching is impossible. You can rig up all kinds of complex server side fragment caching mechanisms, and squeeze quite a bit of performance out. However these schemes quickly grow very complex, whereas the client/server architecture lends itself to a solution that is orders of magnitude more elegant, which is simply to load the dynamic bits via AJAX. This A) offloads processing to the client, B) solves all kinds of caching problems, allowing full HTTP caching where it would have been impossible, and bypasses hordes of thorny cache invalidation problems, C) creates some elegant optimizations that would have chicken-or-egg problems if attempted on a server-side MVC architecture alone, D) Improves page responsiveness dramatically as the initial HTML shell and static assets can start loading almost instantaneously, and E) allows a more de-coupled architecture that makes sharding and scaling much easier.
Because of the technical advantages, it's inevitable that web-based app development will continue moving in this direction. Web apps that don't go in this direction will be at a disadvantage from an operating cost and UX perspective.