[thaumasiotes]

Sean Goedecke articulated a different theory of promotion (at large tech companies; it probably does generalize to large non-tech companies and almost certainly won't generalize to small companies):

He said that you get a promotion for one of two reasons:

(a) the company is afraid that, without the promotion, you'll leave; or

(b) the company wants you to accomplish some task, and believes that you will be better able to do it if granted additional political power.

This post seems to agree well with that option (b). It advises that you make the case for your own promotion based on two prongs:

(1) the success of my project is important to the business;

(2) my project is more likely to succeed if I am promoted.

(The post also throws full support to option (a).)