It's not useless, just unfounded, like the MBTI which is based on making assumptions about Jungian INTJ typology, but is not based in S (reality). Your comment indirectly supports what I've been saying on another thread. For example, the idea that my inferior function is Fe has no basis in my personal reality. It is true in theory, but not necessarily in practice. And it is true in theory only because someone made up a nice-sounding idea about cognitive functions that makes sense in a circular way, but only internally to the theory itself.
Question: if S = reality oriented, then N = ?