The store is in the middle, trying to connect as many customers to the products as possible. But from the store's perspective, the crucial aspect is how much it costs to make those connections, because the store is essentially living on a narrow split between what the makers charge for the product and what the customers are willing to pay. Let's get back to basics. The most important people in the store are the customers that make the entire system work. It's a little more complicated than that because judging computers is a good deal more difficult than picking melons.
Every computer has a bunch of specs, and even the specs only tell part of the story.
But even there, with the selection basically limited to a single brand, there are still various models, configurations, and options to take into account, returning in the end to what the customer wants to do now and in the future. I used to feel it was a mostly a sneaky way to avoid direct competition. One rec equals ten specs' is my proverb here. It's a Japanese word referring to someone who acts the fool to attract customers. A one-man band wearing a signboard would be the American equivalent, and I'm glad the Japanese haven't copied that approach.