Work being deligated to you is a privilege

Getting work from your boss is a privilege. It is only those who deserve the work that get the work.
Beyond skills, it the ability to finish projects and see things to the end that earns one this privilege. If you do not showcase these abilities, I am sorry you do not deserve the work that your superiors would rather assign to your peers.
One of the best movies that expanded on this idea for me was Whiplash. The scene in which the instructor says "Its not your part. It is MY part and I am lending it to you. Earn it" In many ways this is what a manager too ought to say to his subordinates as the Directors will never ask the base employees if results are not delivered. It is going to be his neck on the guillotine if the targets aren't met.

One needs to be cognizant of this when working under an honest supervisor.