The Information notes numerous sources that claim that Apple is aware that off-the shelf and third-party hardware could be tampered with to allow access to data by either nefarious parties or government agencies. It's become so paranoid (and rightfully so) that it even started taking photographs of motherboards and labeling each chip's function so that if a board shows up with an additional chip that wasn't in the original design, it'll know.
But the only truly secure hardware and software system would be one created within Cupertino. By being in charge of the design and manufacture of the chips and boards, Apple would have control of its own security without relying on the cloud solutions it currently uses from Amazon, Microsoft and Google.
Apple's recent fight with the FBI and DoJ only underscore the company's commitment to keeping its users data safe and away from prying eyes. While the company has and will continue to comply with court orders that don't require it to break the encryption on user devices, it still wants to make sure information is only available when its legally handed over to authorities.