What makes you think that? Because I don't see anything in the game that requires talking OOC (well not moreso than any other game), and I do see things that absolutely require not only talking IC, but being in tune with your character's desires and psychology in a very deep way.
From above...
"Dramatic Scenes are the heart of the system, and are encounters between two characters, the Petitioner and the Grantor. The Petitioner wants some emotional payoff from the Grantor; the Grantor may or may not want to give it. If the Grantor gives the payoff up, they get a token; if they don't give it up, the Petitioner can force the issue, which the Grantor can then block. If the Petitioner is rebuffed, they get a token."
Even if players have internalized the rules to such an extent that any IC conversation can lead to the handing out and spending of tokens naturally as breathing, it's still looking down on the characters from above, from the writer's/director's chair, even if they are roleplaying out the exchange.
Kurt, Katey and Charlie can be getting into a very deep psychological analysis of the final scene between Jax and Gemma, and even if they roleplay it out, they're still talking about the characters as characters.
Over the years, I've had hours and hours of discussion about the psychology and structure of the Jax-Gemma relationship with everyone from literature professors to psychiatrists. It's doesn't matter how in depth it goes and how well I decide I know Jax, because I'm still not roleplaying Jax, I'm discussing him as an external entity.
If I'm roleplaying, I don't want or need a system to help me get into my character's head, because I am my character's head. I don't need to internalize the rules of interaction because I've internalized my character, and when he interacts, it's with faults, biases, prejudices, and limited knowledge intact and already taken into consideration. My characters goals are mine. I have no story arc I'm wanting to see happen, my character's motivations are mine.
If you differ, cool. I don't have a problem with people liking Hillfolk, it seems to be very concerned with character integrity, which is good, but un-needed in my case and my opinion.
What I do object to is the notion that games like Hillfolk just "make into mechanics what everyone does anyway" because neither I or anyone I've regularly gamed with in 25+ years does that.
Some people seem to always have and probably always will roleplay "one step removed" as a friend likes to say...they always have a narrative lens through which they view roleplay, so to them, narrative mechanics do simply make explicit what for them has always been implicit. The weird part is that many of them don't believe or understand that not everyone roleplays that way, and thus explicitly making rules for something we don't do at all
changes entirely the roleplaying process.