Here's the funny part: it's probably fine. AND YET, people will twist themselves inside-out to deny the premise.
Your root post fully admitted the accusation:
If you're not in this one store, you lose access to most customers.
That's a fucking monopoly.
As I've explained to people, over and over and over and over, anti-competitive practice is a separate thing. Monopoly just means market share. It's enough power to become a problem. It is the ability to fuck people over. We need to recognize these situations, before they ruin everything.
For comparison, Netflix was a monopoly, and I think the entire world would be happier if that was still the case. But saying so doesn't mean they weren't a monopoly. For a good while there, your choices for legal streaming video were Netflix, or lying to yourself about legality. The desirable solution would be multiple services offering all the same shows for competitive... not the exclusivity hellscape we got. And gaming would be better-off if every game was in every storefront, like boxes on shelves, instead of one store being a huge fucking deal and the rest being nearly irrelevant.