But the cost of the rent is "arbitary" - if amazon owned the apartment, they could set the rent high, and give you a "discouunt". If they get large enough, they can force the high price to become the norm, and so force you to buy the committed spend. This gives them more leverage elsewhere as well (e.g., suppliers).
I was referencing the example from the article, which argues that a $400 committed spend on a $500 discount is a bad thing. If you think the article makes no sense, then my discussion of it will of course make no sense either.
That makes no sense, who wouldn't do that. It would be more like $250 rent discount for $500 purchases.