Interesting, but I don't think I'm getting my point across. Let's take the Suzu route as an example. Now I'll let you know up front that I haven't read it, I'm just using it in hopes of clarifying things.

As I take it, Suzu is the lens through which you see the world and it is through that lens that we experience her coming into contact with Hisao and a romance blossoms yadda yadda yadda. They could form a chorus line and sing showtunes, it doesn't matter.

What I'm getting at is that because we're presented with Suzu's point of view, we're invited to side with her, to sit in the backseat of her car as she drives through the story. In this sense, Suzu is entirely focused on Hisao and not in the reader. We are along for the ride to see her try to win his affections, we find out the things she likes about him, the things she doesn't, the whole shabang.

Contrast this with any of the official KS routes, where we're in the backseat of Hisao's car instead. Because here the reader and Hisao are in the same general area that the affection is going (and the line is blurred by us being tempted to insert ourselves in Hisao's place instead of the backseat), it is easier to see the girl's affection as being aimed at the reader as well as Hisao.

In the Suzu route example, because Suzu is unaware of the reader and directs her affection at Hisao who is a different entity entirely, assuming a romance between reader and Suzu is more like trying to cop a feel from the back seat.

I realize this might be a more confusing way of explaining things than I mean it to, but I hope I'm getting across that unless you write a story where Suzu (or any pov girl) is directly addressing the reader and acknowleding them, she can never engage with the reader.

This is probably another bad example, but it's like having Suzu send you letters about how she's met Hisao and fallen for him, and then your response being to see a romance between Suzu and you instead.