MS Office has been able to do that for years, it's called a Network install, it's slower than snail snot, and it means that when one router goes down productivity dies. That's one of the reasons the world moved to fully functional desktop machines, so people can still work when the network is having issues.
So in other words MS has not been able to give users a realistic way of doint it. Being able and being usable are two different things. Also let me ask you can you run a network install to say an apple box? what about solaris? MS's implementation in addition to 'being slower than snail snot' was also not *portable*. Beyond the fact that MS never tried to optimize office for that behavior, and beyond the fact is was not portable to other operating systems, it was based on MS's network protocols which were never really kind to a network. An implementation in HTTP would resolve all of these.
That's one of the reasons the world moved to fully functional desktop machines, so people can still work when the network is having issues.
The major reason this started happening was because people wanted PC's in their home, and bandwidth at the time *IF* you could even get it was not enough to do anything useful. once people were running stand alone at home the needed applications. Now the glass is out there for people to use and while this may not catch on in the home to ignore client server in a corporate setting because it so 'ancient' would not be a wise decision.