Winnie:
Many of us know rabbonim, dayanim, and poskim. We also know rebbes, roshei yeshivos, and others. It is not my place to assess them, nor to grade them in any ranking order. I oppose the use of age or the percentage of white in the beard as an indication of one’s knowledge. Even among this listing above, there are those with particular expertise in Hilchos Shabbos, others in Mikvaos, others in dealing with medical shailos, etc. You get my point. Your average rov of a shul might do quite well to deliver divrei Torah on the parsha, speak at simchos (or ch”v levayos), and give a great Daf Yomi. That is not a qualifier to guide problems in shalom bayis, pasken shailos in mikvaos, or pasken a shailoh about a possible safrus problem in a Sefer Torah. As in a medical career, where there is core knowledge, there is the specializing in many different areas, and a good doctor refers anything outside of his domain to experts.
Again, I am pointing to the assumption that every “gadol” is a jack of all trades. We are privy to hundreds of anecdotes of some truly great leaders who refused to intervene in areas outside their expertise. Rav Avigdor Miller ZT”L was vocal about a great many areas. But he also deferred many questions to others. That’s only one example of many. We misuse our gedolim. And some rabbonim today assume they know much about certain specialties where they do not.