I've understood that but expanded my understanding whilst you've halted your progress by assuming that the lack of clear delineations nullifies the existence of variation and diversity regarding the phenomena of observation
If one chooses to take the concept wholesale without analysing how it reconciles with reality then yes that's true.
Rather the correction I have found upon the theory is that it's best understood as influencing preferred behaviour in the absence of external protocol that mandates the emergence of a necessitated behaviour. TLDR if it makes sense to behave in an "Fe" manner then we all display "Fe" as it is the most appropriate social conduct available. The idea that an ILI or SLI has to be socially inept and be incapable of caring and adapting to social cues, emotions, etc is asinine; on top of that anyone can become socially inept given the right toxic impetus, or converse learn to develop socially barring those with medical conditions such as types of autism.
In spite of this there is variation, diversity, in what people may ascribe as "Fe" with regards to personality. Furthermore, it is very much possible and evident to see an ILI with superior competence in "Fe" compared to an ESE or EIE - that is superior awareness of group dynamics and emotions along with an ability to influence them.
That there is exactly true, nevertheless there are variations in thought that could be ascribed to the 8 thinking styles. This however is quite abstract but true as evident in how it's easier to share information/thoughts with people whose thinking is congruent with ours.
Actually all thinking is both simultaneously abstract & concrete (as in: deriving in mental projections upon the world whilst equally being of the world and connected to it); despite this there's empirical difference to be felt empirically though hard to articulate. My own father is SLI, but as intelligent as me to uncanny levels with absurd similarities, it made no sense to diagnose him as my identical or quasi-identity, extinguishement or mirror (ILI, LII, ILE, LIE), as I have met people like that who are different from him. There is no mystical sensing - it was just a reductive abstraction of people like that who weren't even intelligent.