> If I'm shopping for an internet-of-things-enabled doorbell, and a brick-and-mortar retailer only stocks brands with a reasonable history of product security...
Brick and mortar might stock known and respected brands, but it may be that they only have the bottom of that brand’s range of products, and if you want anything better the only place for that is an online shop like Amazon. My typical examples of this (in my European country, I don’t know how things are in the USA) are gigabit wireless routers and higher-end bike parts. Brick and mortar typically stocks only sub-gigabit routers, because that is what the uninformed masses want and are willing to pay for. Local bike shops stock only the broadest mass-market parts, with an emphasis on looks (and even some dodgy China brands in there) over longterm quality.
So, assuming that you know what you really want first, Amazon has served you better. (Leaving aside the problem with co-mingled inventory, where you might get a fake even if you bought a respected product.)