USB-A male to USB-A male is not in any USB standard (not entirely true, but compliant cables are very rare and don’t connect voltage), and if you plug it into a device it’s not meant for, the behavior is entirely unspecified. It will probably do nothing. But it might fry your USB controller that is not expecting to receive voltage.

USB-C to USB-C is in the spec, and if you plug in two host devices, they won’t hurt each other. You can actually charge a host device over USB-C, unlike USB-A.

That’s why it isn’t ok. It’s not the same thing, it’s not in the standard, and it can even be dangerous (to the device).