Socionics is incomplete like any other theory. I think it is better to explore and expand it rather than try to contain it.
There is a balance of internal and external messages the brain receives and needs to process on a given day. External affects internal and internal affects external. If type is 100% biological, then we are excluding how external messages affect the brain.
I also think that if there were ever to be a complete theory or even a more consistent one, much of the mystery of human relations would be gone. As much as I would love to *try* to come up with one, I feel as though it would really be a bad idea to know exactly what draws me to another person.
Another thought I am having is that neither MBTI or socionics takes into account the external events affecting internal processing. Most of it is founded on a theory that people are inherently who they are.
When I think of external, I think of mostly external issues related to culture. I have no idea if I would be the same person if I grew up in New York in a poor city with very little educational resources, in an uneducated family, and then moved to an entirely different location in my childhood..etc Idk! What if my trauma has shaped who I am in some way? What if the exposure to intelligent conversation or the schools I went to helped shaped my brain? What if being yelled at as a kid changed my auditory cortex in some way...etc
My thoughts are all over the place, but what I am saying is that not everything is known about the brain yet, how can we actually determine if type is 100% biological or not? Even if you are born with a certain type, surely external events and circumstances can change patterns in the brain.