v1 and v2 UUIDs are derived from a MAC address by specification, the uniqueness of the v1 scheme in particular depends on it. Whether that's a good idea or not

v1 and v2 UUIDs are derived from a MAC address by specification, the uniqueness of the v1 scheme in particular depends on it. Whether that's a good idea or not is another topic entirely, but if you want to conform to spec, an implementation needs to be able to read MAC addresses