$_ is inscrutable if you haven't studied perl, but the same thing would happen to anyone who sees a python decorator for the first time. what does "else: do after a while loop in python? Only people who know python know what it does (and I suspect most don't). The different quoting operators are also trivial to learn. In comparison, yield from python is also simple syntax but the semantics are much more involved.
BEGIN? Take 60 seconds to read what it means. And if you knew awk, you'd not have to do that, as it was directly lifted from awk.