Some further background: vendor instrinsics are well documented and unchanging. They are a lot easier for a language to standardize on. As others have pointed

Some further background: vendor instrinsics are well documented and unchanging. They are a lot easier for a language to standardize on. As others have pointed out, there are higher level libraries being built on top of them. This gives the Rust community the freedom to experiment on how the instrinsics should be implemented with less concerns over compatibility. This also is a nice way of handling a limited subset of other assembly instructions for systems programming while they figure out how to have inline assembly without coupling the language to its implementation.