I use at least 4 different devices on a daily basis, sometimes more. Forfeiting access to things deemed not for children, or I want connected to my ID like banking or prescription renewal, on any one of them because my id can only be on one device, is not an acceptable solution. My phone and gaming machine need equal access to content some would object to others (especially children) interacting with, while my personal and work laptops have hard needs for me being able to prove my identity. And backup devices should any one of the systems I rely on fail need to be able to come up and running in no more time than it takes to get a replacement from the store.