No resources

I learned a lot working at Amazon. But it was unnecessarily grueling work. Most teams are resource strapped. You are ask to do simply too much work for the number of people. This means getting work done from other dependency teams can be challenging. This sets you up for failure so then they can choose only a few people to keep long-term and even fewer to promote. 

The only exception is if you are working on a high visibility project with senior leadership backing, which makes you a high priority and you get to be at the front of the line for everything. In this case, your senior leadership also wants to get promoted so they need you to succeed so they can publicize your project's success while they hide so many failed projects. It's all a game.