Well, yes, that'd be nice if we had a "interoperable universal interaction standard." But now the majority (and soon, almost everyone) will be using the internet on tiny personal computers (smartphones) that run native apps. Using a web browser will become less and less important or even relevant. In such a case the costs of optimizing for multiple run-times makes little sense. Really, abandoning the browser for native apps (in the old days we called them "programs") across the board makes more sense, and leave browsers to what they were originally intended for - document perusal and simple data collection.
And web browsers absolutely suck at UI for applications. Imagine the man hours and effort that went into building Gmail. It boggles the mind. Who would even want to maintain that?! All for something that could have been created as a native app much easier. There's a lot of reasons that people have gravitated towards apps on phones, but one of them is assuredly that the experience is better than using a web browser.
And web browsers absolutely suck at UI for applications. Imagine the man hours and effort that went into building Gmail. It boggles the mind. Who would even want to maintain that?! All for something that could have been created as a native app much easier. There's a lot of reasons that people have gravitated towards apps on phones, but one of them is assuredly that the experience is better than using a web browser.