Like I say, we could also just add it to the spec... But that would be ridiculous, because why would you support telling someone you were a teapot in an HTTP protocol, when the feature is only useful in a protocol for brewing coffee? That would be like taking a programming language's syntax for assigning data objects and turning it into it's own standard for a text file format.
Maybe a time traveler set this whole thing up 19 years ago just to troll people on standards boards.