It's because in large companies you don't get promoted (and so more money, escape the next redundancy axe) by producing good stuff but by being ranked higher than everyone else on your grade.

So you do this by pointing out to your manager all the good things you have done and shooting down anything anyone else does - since everybody knows this and everybody does it you have a catastrophic situation.

Ultimately the only solution if to have them crash their cars into each on the way to work to decide who gets the corner office (gratuitous Richard Morgan link)