As a current Amazon employee I have to say that is pretty ludicrous. If you actually think Amazon could scale back to 10% of it's current employees without losing massive forward momentum and capacity to deliver results then I don't know what to say. All those metrics would suffer greatly in both the short and long term.

In order to scale back that far without suffering negative results you'd have to assume that those 90% of people aren't doing much day to day, so their loss would not be felt, and that is frankly not true and kind of insulting to the hard work that Amazon employees do.

If a company makes a lot of money, does that mean every employee is responsible for generating the money they made? Is it possible to make a lot of money with not a lot of employees? Does Amazon make less money when employees take a lot of PTO?

I'll add 90% was hyperbole.

If Amazon downsized by 90% then they couldnt drive by my house two to three times a day so I can quickly get my prime widgets.

Those aren't employees, so it's ok as long as they keep the capital assets. (I think.)

Just to be clear, I am using the word "productivity" in a very general sense: output over input.

I'm not sure I understand your reasoning. How would any of these metrics not rapidly collapse under a 90% workforce cut? Are you assuming that the majority of Amazon is somehow automated? It definitely isn't.