I think the problem here is that people are confusing HTML (basic syntax) with HTML5 (it's underlining engine and features/abilities). Microsoft is just saying

I think the problem here is that people are confusing HTML (basic syntax) with HTML5 (it's underlining engine and features/abilities). Microsoft is just saying that since they don't have a cross-compatibility layer to deal with, they can tweak and optimize the rendering engine and the code, since it's using the native Windows API and not some middle layer.