I agree that a tree structure can work well for mapping UIs, but HTML does not. It was specifically design as a textual markup language. Its role has been expanded, but it has been done so poorly.
What really needs to happen it a separation of HTML from UI markup elements. HTML will be used solely for textual markup and a new markup language can be used for UIs. This would allow us to return to a proper separation of concerns.
Sure, but that's an argument for creating new paradigms for having instantly available non-downloaded "apps". Right now, if you want a lot of what a webapp offers (100% cross-compatibility with any platform, instant updates, online syncing for free), you're basically stuck with HTML / Javascript.
<strong> and <em> are the recommended ways to semantically bold and italicize text. <b> and <i> don't have any semantics and can still be used where it makes sense.
