[rangerpolitic]

You don't see it because either (a) people don't do it or (b) people are using HTML as a markup language for apps rather than documents.

HTML was created to be used for documents. It was coopted to be used for apps. They really should have come up with a different language for apps.

[dmitriid]

Why people don’t use it in a) would be an interesting discussion. And I fully agree on b): HTML (+ CSS) is wholly inadequate for app development.