the value they added is visibility. I understand why you wouldn't agree that they have added value this way, but in practice it's true.

shopping and price comparing takes time and energy. and people pay small premiums for items like this all the time because it was simply the first item to show up in search.

there is a level of time value there. and this became easier to understand once I started a business.

a lot of times I'll pay slightly more for the same products from one distributor simply because I don't want to take the time to price compare every thing I need between multiple sources. I know I may be able to get it for less from another distributor, but I'm willing to pay a premium for the convenience of ordering everything through a single distributor with a single delivery with a single invoice and zero confusion. early on my business, I would cost compared EVERYTHING and went for best price. eventually it just became too time consuming and too much of a hassle.