I don't get this argument. How long does a manufacturer keep supporting an old port because users have older devices?

The current phone does not come with a usb-c cable because it is older than the MacBook Pros and the Laptops don't come with a lightning cable because not everyone that has the laptop has an iPhone. I'm sure the next iPhone will come with a usb-c cable and then people will complain that they can't charge it with their old laptops.