Apple (and I’m pretty sure ARM as well) does not want you writing programs that rely on its proprietary extensions to the ISA. The specific things mentioned here are either not exposed to userspace or wrapped in API that hides these implementation details so that third party developers don’t have to deal with them. And Apple changes all these almost every year, which they certainly wouldn’t be able to do if they exposed these; you’ll note that some of my experiments that I wrote not even a year ago are linked in the article as being fundamentally broken now.