Whether a toaster or console or smartphone is sold at a loss or gain is an internal detail that isn't even public. It's totally irrelevant.
Another comparison would be a car that can only drive to restaurants that agreed to give the car company 30% per customer that arrives in one of their cars, and there have to be fences around it to make sure you're not walking to the restaurant next door by foot.
I'm not sure I agree with "I should be able to sell anything with any anti-features I want" anymore to a certain extent, since it does affect such a large part of our lives, as general computing machines.
Also which economic theory am I ignoring? Didn't Apple itself enter the smartphone market by massively disrupting the existing players and forcing the entire industry to play catchup for over a decade? Didn't they do this without any regulatory intervention to weaken the market incumbents at the time? Why can't we expect that the next smartphone-level innovation to personal computing will come without similar intervention on our parts?
Do you suppose that means Nintendo, which has sometimes turned a profit on their consoles, should have an open system? Interesting take, and I wonder what, in your mind, the threshold is for "makes a lot of profit." I.e., if Apple cut the price of their devices to make as much profit as Nintendo, would they get a pass?
On the spot though I'd say that that would make Nintendo the ones that should open up their system in my mind though, provided they are making a sizeable (10% including stuff like R&D over the span of a few years) profit.
Legally that has no bearing on the matter though.
And I think if you put your xbox into development mode you can run your own code on it, like RetroArch although I don't know to what extent that goes.