[vlovich123]

Because async based APIs need to return a promise type of some kind (eg Future). You can kind of auto-generate wrapping code to convert synchronous to asynchronous (with some performance cost that may be undesirable) but you can’t generally do the reverse, unless you try to do funky things like pausing/resuming user space fibers (and then issues of lock inversions and things come into play there in a systems level language).