Keirsey didn't create the temperaments, though. All possible temperament combinations exist, those four are simply the most popular. He simply chose the four organizing principles that he thought were best, which were influenced by his knowledge of the Greek humors (Sanguine=SP, Melancholic=SJ, Phlegmatic=NT, Choleric=NF).
In fact, the original four temperaments that Myers came up with were SF, ST, NT, and NF. So NTs and NFs would be here without him, he just reorganized Sensors. I would like to note that I'm not sure Keirsey's approach is the best (though it's not the worst).
One time this ENTJ tutor of mine really liked me and we ended up hooking up. Anyways she was so crazy like ALLLLLL the time. Always thinking I was cheating and telling me she's trying to not like me because I was only half white. Then at one point I just felt like an object to her, all she wanted was sex sex sex sex sex. I felt like a slave! I had to do what she wanted, when she wanted it, how she liked it, I told her she was clinically paranoid and ended it. I don't claim to understand NT's I just let them be in their logical ways and I always let INTJ's and INTP's think they are right even though sometimes they aren't. But yea that's my NF two cents.