I love how this is twisting the truth: "Websites that rely on Flash present a completely inconsistent experience."
The sites I go to on a hand held which require flash, look exactly the same as the ones on a desktop. The experience is usually only different because the developer didn't create the site with small touch interfaces in mind. If an HTML 5 site is developed the same way, it has the same problem.
However, if you view an HTML 5 site with a browser that's only partially compliant, you will not get the same look nor feel.
Adobe didn't force their product into the market. Developers simply used it because it was the best, and continues to be highly competitive in spite of what's popular (in this case, embracing HTML5- an inconsistent standard across browsers).