Competent admirals don’t make for exciting stories though. We don’t see toilets often in TV either, not because they don’t exist, but because we only see toilets when they relate to the story. Admirals in Star Trek are like Chekhov’s gun, we don’t see them unless they’re necessary for the story. Boring competent level headed not traitorous Admirals are just rarely necessary for good story telling unless they happen to be the protagonist dealing with drama elsewhere.