They don't release it because exposing a stable instruction set would kill their ability to quickly iterate, to release silicon with bugs that can be papered over with software fixes, as fixing bugs in chips is very expensive in terms of time to market, and undoubtedly to charge more for what looks like a hardware feature but actually is a software feature.
It's been this way for 25 years and I don't see it changing.
It's been this way for 25 years and I don't see it changing.