because their business doesn't work without it

the warehouses would have to be 20x the size for the same product catalogue

Well, they wouldn't be able to pretend that they are selling from the official store for that inventory. Which I, personally, would be OK with. I've been on eBay for a couple decades, I don't mind ordering from Jack and Jill's Computer Parts as long as they have a reputation I can check. But the current situation where you can order from what looks like the the official storefront but the fulfillment is from a seething mass of "stickerless commingled inventory", with no way to even determine which merchant introduced the counterfeit product? This has been a problem for over 10 years. It's not just the obvious fraud, it's the subtler fakes. I won't buy anything from Amazon where the failure could kill or injure someone. A sun hat? Sure. A charger or food? Not a chance.