There are keysharing protocols; you can do something like 5 sysadmins have a split of the master key such that any 3 of them can access the master account.
There are definitely use cases for keysharing systems like you describe: if we're talking about getting access to a database with sensitive information, or signing a new cert that all our systems are about to put their full faith in. But for the day-to-day administrative efforts, it's overkill and ends up being counterproductive: after a certain point, Alice and Bob write scripts that let them hotkey signing off on my requests.
I worry about those policies when the shit hits the fan and you're trying to fix a production problem hobbled by an inability to do stuff without three fingers on every keystroke.