There are far too many managers who think every software developer is a round peg--a "resource"--who can simply be replaced by another.
Ever been served by a worker at a Mexican fast food restaurant who didn't know how to roll a burrito? How about a sandwich shop where the person behind the counter couldn't slice the foot-long sub without tearing it up?
Okay, it isn't the best analogy. And maybe your experience has been better than mine during lunch hour. But the real point is that software development isn't like making sandwiches. And if you can't even count on consistency in sandwich-making by different people, why would you expect something different in the software development process?