Yes, you get to the heart of the problem - we turned what started of as a document viewer into a general purpose application platform.

Features paramount in a document viewer (broadly, "respect the user's local document viewing preferences") aren't desirable in a general purpose application platform.

A large number of companies/web developers don't think of themselves as offering the user a document to view on their own terms, but rather an "experience" that they want full control over (which means, most of the time: show ads and record user behavior).

If you're offering me a game, fair enough. But if you're showing me my hotel reservation or electric bill, I want a document, not an ""experience"".