[mapcar]

True. In an organization with enough people, it's often more efficient to specialize (e.g., into workers and managers).

I would say that the quoted statement is not an entirely fair characterization of managers (PIs) in academia though. It's always easy to discount the contribution of others and to believe you did all of the work, and believe me, you do a lot of it - but it's not a trivial matter that these "managers" already thought up and won money for the general research direction, and ultimately accept responsibility for the success of your projects; not to mention having to worry about funding you for the duration of your PhD. And do recall that they do had to be extremely patient with you while you were still learning the ropes - so you can't extrapolate your productivity in your last year back to the first year when assessing your cumulative value. ("you" used here in the generic sense)

I won't deny that many managers are asshats as bosses, but their job is not so simple.