If it’s all about pumping up Lightning, why did the iPad leave it?

Because Lightning is too slow and low-power for the functionality they felt necessary for the iPad.

You can’t do real video output over USB2.0, charging current is limited, and you can’t effectively use it for data and charging at the same time.

Your mistake is overlooking the fact that Lightning is woefully outdated.

iPhones have been able to get away with it this long by doing most everything wirelessly and convincing users like you that it’s somehow better to have a slower, less powerful connector on their phone.

They couldn’t get away with the same limitations on a tablet.