Yes, web developers don't use straight HTML because for anything that is not trivial, it's not sufficient The web today is a place to DO things, not READ things. Even if you are displaying "static" data, Javascript frameworks and libraries can help you write code once and then offload browser compatibility and desktop/mobile presentation formats.
If you add all the interactive elements, it gets even more complex. HTML is powerful and provides transparency, but it's not just the MBA crowd moving away from it.
Also, as desktop applications are quickly being deprecated for browser-based apps, there is more movement to frameworks, and libraries.
Vendor lock-in. Accessibility to many tools for “non-technical” users. Groupthink. Bundles and anti-interoperability (see vendor lock-in). Fright of open source. Non-technical executives who trust the wrong people. That’s just off the top of my head.