Maybe it's different methods of pursuing interests. As I said earlier, I tend to pursue things initially the very moment they occur to me by talking about them with whoever i'm with. My ISTJ friend pursues things by looking them up and researching them, and when he considers that he's finished pursuing it,
then he discusses it. This isn't necessarily an SJ thing though anyway because ptgatsby described himself doing exactly the same process and he's an SP. He also said he doesn't like theorizing and discussing
before researching, either. For me the discussion
constitutes part of the research. Is that NP, or just general E? I don't know...
But obviously if your main method of pursuing your curiosity is
not through discussion, it's gonna be easy for people to not notice that you have any! Meanwhile if you're doing the ENxP thing of randomly throwing out your random thoughts, associations, connections and questions, it's obvious that you're going to be seen as a more curious sorta person.
Could also be an IT thing - that the curiosity is expressed inwardly and pursued non-personally, whilst perhaps E's and F's are more likely express it outwardly and interpersonally?
Just a few observations there