I've actually been wondering for a while now. It seems like ST and NF make sense, but NT and SF don't.
An ST uses specific, sensed details, and reasons in a linear, impersonal fashion. Basically, the calculator/bean-counter type. I can see those two going together well.
An NF uses their imagination and instinct to get an idea of the "essence" of things, and then weighs this according to their subjective sense of value. These two also go well together.
An NT also uses their imagination and instinct to get an idea of the "essence" of things, and then... reasons in a linear, impersonal fashion?
Intuition is a highly unconscious, somewhat subjective process. It relies on a kind of vague instinct, a subjective perception that can't be expressed literally. So why, then, would you go ahead and stuff all of that into a simplistic, impersonal box that's better suited to simple details? You're perceiving reality subjectively, and then trying to turn around and throw away all of the instinct and irrational process that gave rise to the idea in the first place, to clean it up and push it through a simplistic, linear, impersonal process that can't possibly capture much of what was perceived.
It's almost like it turns against itself halfway through the process in a half-hearted effort to make an appeal that will be listened to by "bean-counter" types.
So, what is an NT, really? Is it an Intuitive that was forced to discipline their imagination into working with logic? Is it a conflicted person who tried to set up a strange compromise between the rational and irrational parts of their mind? Is it someone who wants to hide/destroy their own sensitivity for some reason?
I know that if you're an NT, you might very well understand how it is they go together, and may even think that N and F don't go well together. I'm just curious as to why those processes should work together, and how they fit together for you.