On your "weary Fi users thread" since it not only excludes SFPs, but also NTJs ...
Fi is selfish, but what people often don't realize is that Ti is just as selfish. For shorthand, let us call the entities that Fi processes "feelings" and the entities that Ti processes "ideas."
Fi users predominantly use Te, and Ti users predominantly use Fe. So Fi is selfish about feelings, but unselfish about ideas. Ti is selfish about ideas, but not selfish about feelings.
For Fi users, it's about what I feel, what I feel, what I feel. For Ti users, it's all about what I think, what I think, what I think.
Fe/Ti tries to communicate with Fi, but can get stuck on this selfishness crosstalk. Fe's feelings are shared: feelings are precisely how you connect with other people. If you're not sharing your feelings, if you do not adjust your feelings to accomodate others, you're being selfish. But remember, this is all because Fe is a primary communication tool: by hiding one's own feelings, by not adjusting one's own feelings in response to others, of course it looks selfish to Fe.
However, the same thing is true between Te and Ti. When I talk with someone using Te, there is a free flow of ideas. The ideas change and alter on the fly, we work together to develop new ideas, to share ideas. We connect and communicate via ideas. Enter the Ti user, who alternately seems like a brick wall, black hole, or source of technically correct and accurate but useless and noncommunicative information (think Microsoft Technical Support). With Te, I can't tell a Ti user a damn thing. I present ideas to the Ti user, who only procedes to pick them apart, accuse me of being inconsistant or incomplete or shallow. In the meantime, I hardly get any clue what the Ti user thinks. I get no "hooks" with which to show him where he might have some bad assumptions. He rejects my ideas based on his bad assumptions, and keeps on saying things like, "I don't understand how that could be true," and leaving me without a clue on which stupid idea he has in his head that makes him possibly think it couldn't be true. Why? Because he has to figure it all out for himself, selfish bastard. He can't trust even for a moment that I might be correct.
Thing is, though, that's just my impression. What really goes on is that he is self-doubting. He is unsure. But it's Ti, so he doesn't express it. He's Ti, so he has a lot of trouble expressing his confusion. If his ideas are wrong, then there is something seriously wrong with him, and he's going to take a long time to refigure them out.
Now, reverse that, and that's how Fe/Ti views us. Their feelings aren't shallow, they just feel that way to us. They share and develop feelings together, with other people as a means of connecting, and Fi users refuse that connection, which hurts them. We reject their feelings (because we feel they're "forcing them on us"), and that hurts them. We wish them happiness and all sorts of abstract positive things, but we don't respond to their particular feelings, which hurts them.
I think that Fe arrives at certain kinds of spiritual understanding faster than Fi. The understanding is shallower, perhaps, but it is no less true, and it is more than Fi immediately understands. However, when Fi arrives at the same understanding, it is much deeper, more thoroughly understood, and implies other truths of which Fe is not immediately aware. I base this off of the Te/Ti analogy: I understand what is true much faster your typical Ti user, which is great for problem solving, but the Ti user will develop a level of understanding I will rarely reach (I'm strong in Ti, but I use it to delve into particular topics, and only up to the point where I have enough info to go into Te mode again).
The big difference between the Fi and Ti cases, though, is that Ti can eventually be translated into objective truth, through real life examples where experiment vindicates theory. Fi truths can't be proven, they can only be discovered for oneself. I can share a pic of hands holding a sun, and explain how that shows me so many truths about life, but other people either "get it" or not.
So it really isn't selfishness, on the part of Ti or Fi. Selfishness is solely an issue of maturity, and this forum in particular has a bad habit of blaming immature behavior on types. The type only gives a basic indication of how immaturity will typically be expressed, it isn't the source of the immaturity.