Amazon managers often have target URAs (unregretted attrition) to hit, around 6% per year in an organization. They are incentivized to fire people who don't perform, regardless of the reason. If they don't do it, someone else on their team might have to go. If they cannot hit URA targets, those managers could become targets to let go as URA.
This is a well-known tradeoff within most tech circles on the risk of working for Amazon. Unlike Netflix, who are clear about a similar policy (though without targets) Amazon does not advertise that they have internal URA targets externally.
I'll also add that from the outside, this setup has worked surprisingly well for Amazon for well over a decade - based on business results and how they became one of the most valuable companies in the world. However, as this policy is more known and stories like the author's surface, it's starting to hurt their brand in ways that hurts their hiring and is forcing them to have to pay more to hire ("would you take job A or job B that pay the same, knowing that 6% of people per year are fired at job A being Amazon?")