Why is Assertive vs. Turbulent not being talked about more? These traits make a huge difference in terms of personality. In my opinion, they make just as much of a difference as a four letter type would. For example, the difference between an INFP-A and INFP-T would be very distinguishable if the person is not trying to hide their true self. I know a lot of people don't trust 16personalities (I don't fully), but the link below is not a bad read.
https://www.16personalities.com/articles/identity-assertive-vs-turbulent
https://www.16personalities.com/articles/identity-assertive-vs-turbulent