Earlier quoted context omitted.
Nobody has ruled on whether the practices are actually monopolistic or not - this ruling just allows a suit against Apple to proceed, which will then make that determination about their business practices. The debate in this case was all about whether the end user was Apple's customer (thus able to sue Apple directly) or the developer's customer.
I think this debate is interesting, but I don't expect Apple to be happy about the final outcome. A developer publishing solely on Apple's App Store (and relying solely on Apple features to provide functionality) has no direct access to the customer* - Apple prevents that fairly well. In this case, I feel like, as a consumer, I'm Apple's customer. I think courts, and especially juries, would agree. That said, I don't…
If my product is being sold in any retail store e.g. Best Buy then I typically don't have access to the customer's contact details that may be collected at the checkout. It's up to me to capture that information when a user uses my product.