The strength of Boohoo and Missguided are that they employ a large domestic production operation. As with Choosy, the founders of Boohoo and Missguided have existing strong relationships in the rag trade from having worked as producers for other brands such as Topshop, etc. in the past.
Despite its connections, Choosy may struggle with MOQs and at what point they elect to manufacture a piece and in what colour/size specs.
A few years ago, Saks 5th Avenue was sued by one of its customers for preventing them from placing any further orders after ordering $150k worth of merchandise and keeping only $5k's worth. However, frictionless ecommerce almost invites this type of behaviour as was the case with the "Zalando Parties" where a group of people ordered merchandise only to return it after having the "party." Banning such individuals might be tricky and may even cost more (in PR value) that it saves. But, personalisation tech might make it easier to limit a persons ability to shop ... not sure about the legalities of such measures though....
Considering the size of the US market and its relatively low population density, it does make sense for grocers to use their store estate as an extended warehouse despite the higher costs compared to automated fulfillment.