Except that the specific example everyone sites is Amazon, and Amazon isn't even in the double digits of all retail in the US [0]. WalMart on the other hand is 8.9% of all retail [1] -- nearly double what Amazon captures. Neither one is that much of the total market. Online is also a surprisingly small portion of total retail still, esp. when you start looking at the magnitude of the numbers.

[0] https://techcrunch.com/2018/07/13/amazons-share-of-the-us-e-... -- 49% of ecommerce, 5% of total retail [1] https://www.pymnts.com/consumer-insights/2018/walmart-amazon...