Why this is a uncommon adapter?
because when both ends are in male, it means you:
1. will need a female end at the other side, which is normally an extender, that will make technically impossible. A USB cable without an active repeater means you can maximum extend up to 3 meters or 5 meters (some people will have it up to 8 meters), no matter how, there is a limitation.
2. you may need to connect the USB-C side directly from device to device. e.g. if you connect it to a USB-C hard drive, then you will one end connect to a computer, at the other end, connect to an external hard drive. Considering the super short the distance, it will be a hassle each time you do it.
Anyway, we made such one: