One thing that Python has that virtually no (well okay groovy and nim do too) other programming language has is whitespace for blocks rather than visible braces (or even BEGIN/END ala Wirthian languages). That's something much like line numbers in classic BASIC that introduces a roadblock when learners move on from it.
I don't know if it's that hard for people to go from Python (where whitespace is significant) to languages that use {} and the like. But hey, people only hire me when they want people to learn Python, not when they're moving away from it. :-)