I'm guessing they are just looking at iPhones and tablets, none of which typically are set up for multiple users.
They also don't limit an iPad to just one account. My iPad is sync'ed to my wife and my own laptops. It has apps from both of our account. I can play them anytime I want without resyncing/wiping the iPad content. Software updates can now be done on the iPad itself.
Then, you can log in and out of GameCenter to capture your achievements/trophies to different account.
On top of that, it will automatically sync downloaded content to multiple iOS devices.
Sony's new system may be too restricted. Perhaps it is a system designed for businesses after soliciting developers and retailers input. But this crude DRM system will not buy them consumers. I guess we'll see how much more $$$ they make out of the strict DRM in the west, and if they get additional exclusive developer or retailer support.