How would Apple know about a new iOS device or Mac signing into your iTunes Store account? It learns of the device the first time you successfully login on the device. Besides doing some sort of pre-registration or requiring an iTunes Store ID to simply buy the device there's no easy way around that. They'd also have to end all used/third party sales of Apple products or require resellers to activate every iPad, iPod Touch, iPhone and Mac they're sold. It's completely unrealistic to do a default deny on new devices.