cloud computing is not reliable, as instead of just worrying about your OS and hardware messing up while working, you now have to worry about your PC hardware, OS, internet connection and micosoft's servers having any problems causing problems for you
On top of that, you will be reliant on an internet connection to do things that didn't require it in the past.
Other than it being less reliable, you have additional vectors of exploitation as well as a internet bottleneck.
All forums of online DRM even if they can function offline will eventually require you to log online.
For example, steam allows you to play in offline m,ode, but not forever, as steam has a little flaw, what is stopping you from buying a game, installing it then having all of your friends log into your account and install the game, then everyone plays in offline mode and enjoys the game at the same time.
If the os can work offline, it will eventually want an internet connection to make sure that you didn't turn into a thief while offline.