It wasn't a good idea. 'political' wasn't concretely defined, and so the ban just made it easier to flag any topic you don't like by way of a shifting definition of the word.
By my understanding, "most" officially means "uninteresting", and extra-officially means "those that make the comments section devolve into a flamewar" (which, in turn, means "most")
You're wrong about "there never was such a rule" too.
https://news.ycombinator.com/item?id=13463480
> Off-Topic: Most stories about politics