Microsoft is not alone in saying this.
Other than Sony, who's opinion is so far from impartial on the matter that it's basically irrelevant (unless they want to backtrack on their own Bungie deal that was done to launch
their own GaaS system), other game publishers (Ubisoft and Riot in particular)
have given sentiment to regulators for Brazil very similar to what Microsoft is saying to New Zealand. Some of that is probably pretentious arrogance on the publisher in question's part (Ubisoft...), but Microsoft still isn't the only one saying it.
I feel it's also hard to argue that it's true that even Call of Duty is something that it being exclusive to a single system (which Microsoft has repeatedly noted would not be done anyway, but even if we assume there's some sort of technically correct gotcha buried in their statements) would doom all competitors. Microsoft name-checked Valve, which is a bit of an apples/oranges comparison but still a point of comparison to make; but more directly there hasn't been a Call of Duty game on a Nintendo system in a decade and there's no irreparable harm to be seen there. The only company that would be harmed is Sony having spent the entire previous console generation paying Activision handsomely to have the CoD franchise be associated as being a
Playstation franchise that happened to be playable elsewhere that they would (obviously) immediately lose if Call of Duty becomes a Microsoft franchise (even if it remains multiplatform); but making moves that aren't beneficial to your competitors aren't inherently antitrust issues.
