I think in the process of the maturation of Fi dom/aux they actually do tend to have a deeper understanding of other people because they learn to value the fact that other people have different value systems.
The paradox of the Fi dom/aux is the personal universal values. I've seen the INTJs say this is an oxymoron, etc. but I don't think so.
Fi starts out with personal values, sure, but as the person matures they will note universal values, oh yes, I think they will. I think they're highly likely (especially when Ne users) to notice patterns of human ethical values in different cultures, underlying humanity.
I also think the strange thing is that we can defend our own values so fiercely, to the point of seeming disruptive or like outsiders, but when we're in a mature, rational Fi state we're so aware of how other people have their right to have values too, and how it's all circumstantial and shifting, etc.
Fe has a similar complexity and seeming oxymoronic quality: they supposedly are always focused on other people, caring about the best interest of the collective group, and prizing harmony over standing up for individual values...but on the other hand they also impose social structure onto others (which seems willful rather than others-centered or harmonious) and in some cases (particularly in cases of Fe/Si) will almost stupidly adhere to "social order" even when it's completely irrational, non-sensical, and has nothing to do with anything.
Neither Feeling function is simple or one-sided.