No need to apologize to me for being too theological. I'm probably starting seminary in about 6 months, and currently act as one of the lay-ministry leaders of my church. That flaw you point to assumes a rational actor model, which is itself flawed, especially when dealing with individuals. I'm a person. I have faults which I can be aware of, and work to overcome those faults. I can also help people to work on those faults in themselves, even if I haven't yet overcome them. If I can't do this, then I have no business being a religious leader. Example: one of my faults is that I'm shy about romance. I can overcome this fault, I hope. But I haven't yet. If a friend comes to me and seeks advice from me about how they're having trouble meeting women, and it becomes clear to me that he's engaged in the same kind of self-sabotage that many shy men, including myself, engage in, do I better serve my friend in this case by remaining silent simply because I haven't yet overcome that fault in myself? Or do I suggest to him that this might be his problem, acknowledge that it's mine too, and offer whatever little insight I might currently have on it? You're right, it would be better if I had overcome the flaw myself, though I would suggest that it would be worse in many ways if I never had it to start with. People who have never had problems with romantic shyness basically just say "man up and do it," which is all well and good, but doesn't really help as much as talking to someone who struggles with the same character flaw.
Your objection also seems to assume that personal experience is the only authoritative source. Psychologists can draw on a body of research. Ministers can draw on scripture, theology, and philosophy. Friends can draw on any personal knowledge they may have. Perhaps that authority isn't as good as my personal experience, but it's none the less valuable. Put in very simple terms, I can say to a child "you should brush your teeth twice a day," and if I look for it, I can find significant research showing that this habit is of benefit. I can do this, even though I often only find time to brush my teeth once a day. I am preaching beyond my practice: I am saying "we aught to do this," while (hopefully) acknowledging that I don't always succeed at doing it myself.