I have been conditioned to write code that is 2/3 compatible, that even when I am writing specifically for the PY3 interpreter the code turns out to be a __future__ import away from being valid PY2. I did not think much of them at first, but very recently, f-strings have changed that.

I think many people get imprinted with writing the PY3 code using only the features available at the time they switched over.