It doesnt actually matter what the almost exclusive use case is, the sheer ability of being able to transmit data in this case and other available uses makes the apparent need of a chip. Keep in mind these chips bring safety to the exposed pins and some negotiation is needed to understand whats on the other side of the cable in order to better handle it. (That and to make it possible to control 3rd party market accessory) A charger is considered an accessory because it is merely a utility for a device, it is made to charge stuff. Take a purse for example, it merely holds stuff and nothing more, you can change a purse and the other one will do the exact same job.