The point is, if you don't want to support spares for your device, you have the option of using standard parts. If you want your own part, you have to either m

The point is, if you don't want to support spares for your device, you have the option of using standard parts. If you want your own part, you have to either make it available, or you have to make it reliable enough that you don't need to. That would remind the incentive to have parts that fail be profitable. Making unreliable and unserviceable devices should cost you more.