Nothing prevents you from installing it on any device that can run it, nothing prevents you from using it for whatever purpose you want, nothing prevents you from pirating it, nothing prevents you from playing there any game, installing application from any source, nothing forces you to use there any IDE, any gaming engine, any API, whatever you want. It does not turn your PC into a brick if you did not disable Internet when servers are down, it does not require to purchase you a specific device to use its services.
Office is in interesting case though. But it has competition, just the competition is nowhere near as developed as Office (they are not even trying and shabby at best) and MS does not enforce you to use Office either. As far as I recall you can implement you own editors that use .xlsx and other formats. MS just have a very solid foundation that it developed through the years. It is not even act as a monopolist anymore, trying to suppress the competition.