I think it is more than just "accepting yourself". I have found that one of the best things I can do to convince people I am competent is to know those things I should not give opinions about because I just don't have adequate information. Admitting "I have no experience with that" (or some similar limitation) tells people that I am not simply being willfully unhelpful but, instead, I am trying to avoid giving bad advice. An awful lot of smart, educated people fall victim to the feeling that they must have an opinion or answer on anything that comes up and get themselves in a pickle by then saying something really ill-informed. Knowing when to say "I simply can't help you with that because I lack adequate knowledge/skill/experience" is relatively rarely done and is psychologically powerful. I used to think it gave an illusion of greater competence than what you actually possess, but perhaps it works in part because "do no harm" genuinely provides superior quality than willy-nilly running around trying to work on things you aren't really qualified to do properly.