Although I mostly agree with the "hurr durr" point, that's not really the reason we're not getting Mario Kart 9 on the Switch. Thread title is the reason.
Nintendo would be smart to make Mario Kart 9 for Switch, because that's part of giving Switch a long lifecycle. Now that Switch is Nintendo's only console, it's a lot more feasible to see more big titles release. There's no good reason to make no Mario Kart 9 for Switch.