> Wal-Mart and Target are the 'curated' everything stores.

Are you talking in-store or online? If I go to walmart.com or target.com and search for "usb cable", I don't see a dozen cables that fit 95% of use cases like in the store. Walmart shows thousands of results, the vast majority of which are marketplace sellers selling through walmart.com. Target has "only" 753 results, 600+ of which I find are not actually sold directly by Target if I dive into the filters. Basically it feels like Walmart and Target are trying to turn their online shopping experience into amazon.com.