Well, I like the story here, but it's kinda against a bit of a strawman. Don't get me wrong, I'm not losing the overall point of the piece, a point I agree with, but that said a metrics focussed manager could have simply added an "adjunct" label to the stories and had this "worst programmer" add themselves to stories as the non-lead developer. Ultimately the best way of measuring programmer productivity is by the ass…
I believe that’s the conventional approach in Python, though? It is a duck-typing language, try-except is a legitimate way of seen if an operator works on an object, and objects should do sensible things with operators. The funny example is that the hasattr built-in just tries to getattr, and then catches the exception to tell if it has the attribute.
The fact that the language doesn't have your back means you need to be more careful about types, not less. The type of the arguments is a function precondition. It's the callee's responsibility to document preconditions and ideally recover cleanly from a violation, but the caller's responsibility to ensure preconditions are met. Illegal states should be caught early, not allowed to percolate until an exception is thrown.
I don't much care if what I just wrote is "Pythonic" or not. I don't think too much careful design up front is responsible for every Python codebase I've ever seen reading like Finnegan's Wake.