Before I understood the host/client nature of USB, I was convinced this magic non-existent USB-to-USB cable would let me connect any PC to any PC and copy between them like giant flash drives.
Looking it up just now indicates that such products still exist. https://plugable.com/products/usb3-tran
The usb-c version of the same is even more confusing, either it's a normal type-c cable and the software is all you get, or it's a cursed bespoke type-c cable that will haunt you for years.