Quick aside, there won’t be a USB D (unless the USB people change their mind yet again), it will be something different from USB. The idea was to have USB A be what you plug on your source and B on your destination and was designed as a way to avoid power surges in the original 1.0 spec because the A side was physically different from the B side you weren’t ever going to plug in something that sends power to something that receives power (basically it prevented users from breaking their devices on accident). USB C changed that with a chip on each cable that handles negotiation before agreeing on a power spec