I personally don't think inferior functions are always negative. I think they can be positive, but you cannot lead with them. The "Fi-Si loop" and "ESTJ shadow" are the ways in which you see Si and Te coming out negatively in an INFP, and yeah, those are big traps (I think every type can fall victim to their shadow or a dominant-tertiary loop). Ideally, I think they can provide an anchor to reality.
Wait, tell me again how introverted functions, particularly introverted judging functions, can become an anchor to reality?