Nobody in this context, refers to the collective. I agree that its important, but arguably Big 5 is "more" important than MBTI even though they are somewhat identical. As MBTI is using Jung's theories, which have likely influenced, but been crafted into the more well developed Big 5 over time slotting in with other famous psychologists views. Looking through the history of the big 5 there is lots of influence and still discussion today as to whether the fact that they "run together" means that there is only 2 rather than 5. I just did a bunch of research on the Dark Triad and they were discussing it there. http://scottbarrykaufman.com/wp-content/uploads/2013/08/jonason-et-al-2013.pdf
So as an example, T types are more likely to score higher on the Dark Triad, due to low agreeableness - which is what makes them T types. Which is why T types, according to Myers Briggs corp, that T types tend to be more dominant in Men, and F in women, because it is testing agreeableness - it has a similar percentage base for the gender dispersion in Agreeableness in the Big 5.
Ni in my opinion is correlated to high consciousness + high openness to experience = someone who constricts their openness. Which is why people with high Ni are more rare in the population, because these are traits that usually run opposite somewhat to each other. As orderliness (in the big 10, one of the two branches of consciousness) restricts creativity (openness to experience) - so most people's brains either become creative OR orderly, its hard to manage both. So something like INFJ/INTJ etc, their brains are a much more complex place because from what I can make out - their grinding against themselves. Whereas say ENTP/ENFP, has less orderliness by default, so its just wild creativity - but can be "too" creative, and get them into trouble because there is no restriction and they have to learn it over time (inferior Si - to develop that sense of low order) - but Ni vs Ne, means the restriction is build in - other types have to "learn" to develop the traits they were not as developed with at birth. The big 5 doesnt "change" though. Your personality is inbuilt at birth generally - from all the studies ive read - it implies its unchangeable in a general sense. Similar to IQ, you can argue you can get 1 or 2 points by doing a very small group of things, ie, having enough food when growing up so your brain properly develops, etc. But in general, these things are all inbuilt from birth as is genetic.