"I don't see what any of this has to do with the initial premise that the web provided a way of avoiding the complexities of cross-platform development."
That was not the initial premise. It was about the web supposedly removing the platform dependencies. Not the technical ones but the business ones - basically an unremovable third party between the developer and their customers. Here's an example of such an article by Tim Bray:
http://www.tbray.org/ongoing/When/200x/2003/07/12/WebsThePla...
Quote: "You’re not a sharecropper, especially not a sharecropper, if you’re building on the Web platform. If you can define your value-add as a series of interactions via a browser, or an interchange of XML messages, nobody can whip the land out from under you."
The above is no longer true. The Web alone is not enough to avoid being a sharecropper.