My mother is ESE-Fe and probably so/sx and e2.. she is like.. the most popular person I ever met.. I barely if almost never met someone who didn't like her. She da queen bee and very kind on top of that.. it's hard to dislike her. So I agree with your theory.
I as an introvert and Ni-dom though and more of a natural outsider I have hurt my 'so' in the past.. Ti-Ha can be very annoying for people and being a dramatic Beta-bitch can stir up lots of drama. But I always was able to relate to the popular and unpopular and gain the favour of people of both 'groups'. I just honestly don't like most people, so it is hard for me to stay focused on people, since I am not interested in most of them (in certain cases to protect myself socially though I indeed become interested in a person, whom I usually wouldn't have been interested in). It's true that so/sx has a hard time focusing on people they aren't interested in. But I do have very special and deep bonds with two other so/sx's. I always struggled with social aspects in the past.. but was able to control it since some intense experiences and feel better about it since then. I met quite a few Ni-doms that said they were told there was something wrong with the way they are/think and I think so-first Ni-doms feel thus especially pressured (just my own theory though).
Someone in the so/sx thread stated that so/sx people will indeed show whom actually is in their favour. And that is very true.. I am very loyal to my squad.. AND someone else said so/sp are usualy the ones who initially and naturally are more popular (I can kinda see it), but so/sx has the potential to become ultimately popular. We also value life-long friendships aka 'the bestie'.
I could see so/sp as politicians or yes I even know a young German actress who might be so/sp.. I feel they are more the sophisticated, resource-focused social people.. so/sx are more part of the common 'people'.. more likeable in general.. more grounded and indeed very 'human'.
But we still are aristocratic bitches when it comes to close friends. Like I am very picky with my close friends.
Yes sp/sx people seem very 'real'.. my former friend didn't really care about my social status at all.. she just accepted me.. very tolerant folks.