It is general purpose computing from the perspective that a client company can build anything they want with it. Which is not true for Apple products. They are end user products aimed at the end consumer.
You are very wrong about this statement. You can't take a Dell/HP/Thinkpad laptop and transform it in the car multimedia device.
You are confusing computer parts with devices. Yes, it is true Apple won't sell you a CPU to put it on the motherboard of your choosing, but it is also true they don't operate in this market.
