>Amazon tried to push off a core cost centre from their business
This is absolutely not true.
Customer reviews were conceived of as a barrier to entry that could not be trivially recreated by competitors. They were also conceived (naively, as it turned out) as inherently more trustworthy than anything created by company editorial/review staff.
There was never any question of "well, we could do reviews ourselves, but ... nah, let the customer do it". The goal was to harness a subtle kind of network effort to do both of (1) improve the usefulness of the site for users (2) create barriers to entry.
This is absolutely not true.
Customer reviews were conceived of as a barrier to entry that could not be trivially recreated by competitors. They were also conceived (naively, as it turned out) as inherently more trustworthy than anything created by company editorial/review staff.
There was never any question of "well, we could do reviews ourselves, but ... nah, let the customer do it". The goal was to harness a subtle kind of network effort to do both of (1) improve the usefulness of the site for users (2) create barriers to entry.
[ EDIT; s/others/users/ ] (#2 amzn employee)