[sbuk]

"It might be trivial, but it's trivially true." It's trivial to the point of not being relevant. If the justice system were to punish every manufacturer that had a monopoly over their own product then nothing would get made. Cogent isn't perhaps the right word. As statements go "$megaCorp has a monopoly over their own products" is meaningless, yet it is constantly cited in these discussions as reason to pursue damages.

[anotherthrow]

Look, there are several issues here. There's a narrow semantic point. On that point (which I think you explicitly denied), you can have monopolies over market segments. Personally, I like semantics, and think semantics is often less trivial then people suppose, but I accept others may be less interested.

Then there's a legal point about whether one opens oneself to legal action for dominance when operating in certain ways over market segments - I think it's also true you can be. But I'm not that advanced in my legal training, so don't take a strong position on that.

Further, there are normative and moral issues about what should be the law, and what one should do in these cases - but discussing those would take a long time...