Likely surface area and dependencies. Nothing is stopping you from using Python with some of the GUI automation packages. Sadly I'm not aware of any that are cross platform, then again neither is AHK or Auto it.
Let me start by saying that I appreciate the humour here :) However, in actuality...
Python is from 1991. Python 2 (from 2000) was not a breaking change if I'm skimming the "what's new in python 2.0" correctly. Python 2 was supported until 2020 (29 years).
Autohotkey from 2003 (19 years old now).
Unless AHKv1 is still maintained, Python wins by a decade.
Ahh, I was supposing if AHK had been written in Python, starting in 2003 because that's when AHK started, it would've experienced a breaking change in either 2008 or 2020, when Python 3 came out or when Python 2 ended support.
Either way, yes it was just a cheap attempt at a joke, thank you for seeing it as such! Python pedantry isn't my strong suit, obviously.