They could have lost enough brand name vendors who decided not to deal with amazon because customers get counterfeit or expired products. Nike and Johnson and Johnson are mentioned in the article, but there are also smaller brands like ThermoWorks who were staunchly anti-Amazon because of co-mingling until very recently. I suspect it was due to a promise to end the process which brought brands back.

Due to a lack of a presence by name brands, Amazon has been devolving into a platform for selling drop-shipped no-name Chinese products. Whether this scared them because of long-term sustainability, tariffs, or just practical business sense is unknown.