My impression is that Microsoft has sweated the details of Excel, the way that Apple sweated the details of the iPhone, so that it is extremely smooth and quick. This in turn makes it literally less physically laborious to use. Things like casually swiping the mouse across a range of cells to select them.

I suspect making it work this way requires an army of developers and some corporate will power. Having an inside track on exactly how the OS works may be an advantage.