I think GP is wrong-as-intended, but is still somewhat correct-as-written, indirectly.
Amazon's growth has pushed various companies out of business, reducing employment opportunities at companies other than Amazon. So any employee who works at Amazon for lack of other opportunities, and if those other opportunities would have existed if Amazon hadn't put them out of business, then yes, that employee is poorer.
This scenario is somewhat contrived on an individual scale, but it seems obvious to me that corporate consolidation and monopoly-ish-ization should lead symmetrically to monopsony-ish-ization in the labor market. But I am not a professional economist and I would be interested to see any actual research on this topic.