Only cares about the top

Amazon managers are taught to only care about the top 10-20% of their direct reports. This is true across the company from engineers to FC workers. This comes from the top of the company, as Jeff Bezos has emphasized from the early days, according to a friend who has worked here since the early days.

I guess there'd be nothing wrong here in terms of being a merit culture, except that many (if not most) of the so-called top-20% got here by backstabbing colleagues who outperformed them. Thus, the top 20% ends up being the most dishonest 20% and where does that leave you in terms of their influence on Amazon culture?