Rather than provide an academic argument as to why HTML5 apps are as good as native, it would be better to provide great examples of where it has worked. Even Steve Jobs originally thought web apps were all you needed but he was eventually convinced otherwise.
In short, how about some proof by example? Lots of examples...
Because the iTunes platform is written in Java with a legacy web framework called WebObjects. Also the iTunes business unity has more characteristics in common with Amazon than Apple itself. That's why we're stuck with a thin client for the AS.
> There is no question that native apps provide better UI's
This is was me talking about mobile. Then I went on to explain why. So I don't think I need to provide any examples there.
As for HTML5 on the desktop you can peruse the Chrome Web Store to find some good stuff. iCloud.com is actually an excellent example of HTML5 done right (for the most part).
As you may know, iCloud is written in SproutCore. If you compare the development process and programmer productivity of SC with let's say Cocoa, you'll see SC can't get near Cocoa in these aspects. It's a mess.
Try iCloud.com on Mac Safari, it's quite nice. Not sure what browsers Apple is targeting for this.
My assumption is that the 5 major desktop browsers can host web apps of this quality if the app developer chooses to target them. Hopefully as time passes the "chooses to target them" part won't be an issue if standards-compliance is a norm.
In short, how about some proof by example? Lots of examples...