I don't know offhand, it's a different team that runs it. I'd guess it's something related to backwards compatibility and the general "roll big changes out slowly so it doesn't break" credo. And it may be tied to a certain kind of HW that supports it, which doesn't exist everywhere, since cloud providers can't just throw out all their HW each time a new feature comes in (as much as we wish we could). But that's just a guess.