I think the main reason shared role accounts are worse then individual accounts is because it is easy in a computer to change a role, but harder to change the a

I think the main reason shared role accounts are worse then individual accounts is because it is easy in a computer to change a role, but harder to change the accounts for many people. With hardware, changing a "role" requires swapping logic inside of every lock that for the user's key: the lack of an abstraction layer makes it impossible. So, in the mechanical world, key-per-group is equally expensive to key-per-user in terms of replacement costs, but far harder to implement.