Not only is it very political, but it forces some baffling decision making.

Assume I have a team of 10 in which 5 are wonderful contributors, and that, due to stack ranking practices, only the top 1/3 of my team gets consideration for big bonuses and promotions. Here, I'm incentivized to immediately hire 5 warm bodies, thus ballooning my team to 15, so that the top 1/3 get the recognition they deserve.

It's actually rational to do that if I'm concerned that those 5 excellent performers will leave without that recognition. The incentives that appear due to stack ranking are really, really bizarre.