Project Managers, manage upwards. Programmers manage downwards.

A Programmer's job is to write bug-free code that delights customers as quickly and cheaply as possible. A Programmer manages there code (downwards), thus if they do a good job there code is happy. The code does not pay there wages and those that do, do not understand the code.

A Project Manager's job is to predict schedules and help the programmes (e.g. make project run faster) A Project Manager spends little time doing anything to help the programmers (managing downwards), and if the project is late they blame the programmer. By isolating the programmer from the upper-management/customers they are able to manage the upper-management/ customers, thus influencing these with the money (managing upwards). They may enrage the programmers, but this does not matter as the programmers are not paying them.