these big companies want to control everything. every scrap of data on your machine every program you use, everything. Microsoft with os and apps, valve with steam and game control updates etc. apple with content etc.
i think this is one of the reasons gaming on the pc has lost out to consoles. you cant get a game toss it in and play like a console and you cant install and play like before, you have to install and register, and update and update and update. they strangled the life out of the platform.
some people use computers for online stuff, facebook etc. and for them with a fast connection cloud is fine. even some apps like office and others work ok with a cloud computing setup.
i saw a show about startrek once that said it was unrealistic because noone uses centralized computing anymore but it looks like we might be moving back to that.