Would you say that either one has more/better free resources available on the internet? That could be a catalyst for discussion... of course, lack of resources elsewhere could potentially lead to more discussion here, as well, but I'm not sure which effect would be stronger...
You're not far off the mark, Z. The difference between what is available online and what is in books can vary greatly. People are having discussions based on different information sources which frequently conflict and contradict. How can people possibly come to any form of mutual understanding? I have several books on the enneagram that go much deeper into type than what is online. So much so, people might kick the type right out of their profile after reading the books.
As far as conflicting sources of information for MBTI type, imagine an online source using Lenore Thomson's name in its title (The Lenore Thomson Exegesis Wiki) posting information which completely contradicts Lenore's comments in her book.
Excerpt from wiki:
For example, Jack Groverland, presumably ENTJ, preaches to "be still" and "tune in to what the greater intelligence of the universe wants you to do." A great many ENTJs seem to preach primarily that reasoning and intellect have limits, and it's critical to learn to perceive in a direct way, not limiting yourself to what you can prove "logically", but tuning in to the totality of everything through a sort of direct perception. A favorite preaching of ENFJs and ENTJs is that you are "responsible" for creating your reality by the kind of attitude that you choose: the world isn't doing things to you, you are self-selecting for certain kinds of things to happen to you by the way that you assign meaning to things and lead yourself to perceive one way and not another. This all sounds very much like articulate descriptions of introverted intuition--straight from the horse's mouth, just it's these horses' secondary function.
http://greenlightwiki.com/lenore-exegesis/Attitudes_from_the_Horse's_Mouth?version=8
Clearly, Ni is not something that is ignored or undervalued in that excerpt.
If anything, the excerpt suggests Ni is valued more than Te - hence the title of the article: Preaching the Secondary.
Now, contrast that excerpt from the online wiki with this comment from Lenore Thomson, in her book:
ENTJ's are more likely to deny introverted intuition in themselves.
The first information source paints a picture of, if anything, putting
more emphasis on Ni than Te. But in Lenore's book, she basically claims an ENTJ would
deny Ni's very existence. Talk about conflicting and contradicting information!
It was Lenore's book which was at the heart of nearly every argument I had with a certain ex-member. This is why having discussions can, at times, border on the absurd. We have no way of knowing what source(s) people are using to spark their comments. If people are operating using sources which conflict and contradict, discussions will then have the potential to emulate that same conflict.