I think big box stores are popular largely because it would be inconvenient to drive between many smaller shops just to find the same variety of goods. It’s the same dynamic we see with car-dependent shopping malls, where the main advantage is being able to park once and visit multiple stores. If instead you had to re-park at each individual store, the experience would be far less convenient.

But if a town is designed to be fully walkable so that people can easily walk from store to store (similar to the experience of shopping inside a indoor mall), then I think the appeal of large one-stop-shop stores is greatly reduced.