I don't think he's talking about pure PoV as much as keeping the player on the same page as Noct. While he does say that "The world and the events that Noctis sees are merely things that are seen through his eyes," that part is restricted to "the events that Noctis sees," with the general rule being that they "placed importance on the main characters and for the player and Noctis to share the same experience when we tell the story."
While some scenes are shown from PoVs other than Noct's, none of them really make the player privy to information that Noct couldn't have at least surmised given his current level of knowledge. In fact, some of the alternate PoV scenes -- most notably, the Luna flashbacks -- are withheld until Noct does have reason to believe something of the sort would have happened.
In other words, while not every scene is from Noct's perspective directly, they're all at least consistent with his current mental state and don't result in significant discrepancies in the experience the player has vs. the experience Noct has. This affects flashbacks to Noct's youth, too, which show up when they become relevant to Noct's current mental state.
(Even something like adding a Gladio scenario to Chapter 13 would be subject to this rule, for what it's worth -- Noct might not have seen what Gladio was doing, but he'd probably have gotten the gist of it.)