"Everybody rises to their level of incompetence."
This is the basic principle governing large organizations, explaining why they work (or rather, don't work) the way they do. The effect is due to the fact that somebody that is INcompetent at his or her job won't be promoted, but that demotions are not done.
The principle is named after Dr. Laurence Peter, who wrote a book called "The Peter Principle: Or Why Things Always Go Wrong" discussing this phenonemon.
Also the name of a british TV-series (named after the above.)