Which point of the story do people actually mean when talking about "Back when Naruto was actually about ninja"?

I suppose it was around chapter 10 up to the death of Zabuza and Haku or so, equivalent to episode 6-9. When there are indeed some themes of hiring mercenaries, bodyguards, and corporate interests happening. Otherwise the first 9 chapters / 6 episodes, and the following ones, aren't much about ninja.

If they're talking about analogue to the historical ninja, that would be during the time of Madara and Hashirama's childhood, or the warring states period, which took place long before the main story to begin with. That was when the "ninja" concept in naruto were the closest they've been to real ninja.

More or less, I think naruto is mostly political with a lot of epic and fantasy poured in.