If it makes you happy we can add in ".. except for soaps" in the ruling... /s

For a real life example, the major grocery chain in Australia (Woolworths) did this with milk, selling their brand for $1 a litre, where everyone else had to do $2+ just to break even.

Effectively selling it at a loss so that they get market dominance. They make up the loss on other products in their big chain.

I think there needs to be a break-up between "the retailer" and their home brand being sold there, because it means the profits made on selling the competition works to the home brand advantage.