I think that the internet attracts ISTJs as much as any IN type. Unless "N" encompasses a lot of concrete thinkers, my inclination is to think that many, many of the INTJs online are ISTJs. Actually the INTJ forum culture feels very much like an ISTJ world when I was hanging out there. I love ISTJs also and they could easily include characters like Scully and Monk. They are very clear, linear, logical, specific, and methodical. I suspect that people who are genuinely INTJs have much more of an ethereal dimension to them. There is a different feeling, although Si can also have an idealistic, almost abstract quality to it from the way I understand it. It starts with the concrete and abstracts it inwardly. Ni takes the "big picture" or an already abstract conception of it and internalizes it, so it could almost be described as twice abstracted. I find it is easiest to describe it as an almost statistical thinking, especially when applied to Te because it is attempting to negotiate a sense of "everything", so it will think in approximations and overall tendencies and currents. ITJs who are extremely specific in ideas are much more likely ISTJs.
I think that all the INs are over-typed because Kiersey wrecked the Sensor categories in his book. He didn't understand the rich and broad nature of it.