The spec doesn't govern what applications can and cannot accept, it governs what contents are valid in tokens. 'None' is valid, that means my parser library will accept it, it doesn't mean my application must accept the token as valid.

Example: The fact that my service has an http stack which must parse a cookie header doesn't mean my app must accept its contents as valid. There's a lot of confusion on this thread about which components should/must do what things.