Is $object_type truly required with register_taxonomy()?

So I dug into the source and discovered that even though the documentation STATES that $object_type is “required”, there’s nothing in the logic that makes this so. $object_type is just added to the properties of the tax object, which presumably is also done when you register the tax while creating the custom post, and also when you use register_taxonomy_for_object_type(). I tried creating a custom taxonomy with null for the $object_type parameter, and then assigning the tax when creating the custom post type and it worked as hoped-for.
Codex updated.