I would disagree with this. Just because someone is a CFI doesn’t mean they are more knowledgeable the a PPL. There are tons of PPLs that have far more knowledge and experience than young CFIs.

My last BFR was a perfect example. The instructor was fairly competent, but not particularly experienced and was unaware of a lot of things. We actually talked at great length about some of the things that she lacked knowledge on. Much of her knowledge came only from the books and lacked any experiential application. Her understanding of the physics of flight was largely rote memorization.

Qualifications can only measure to a point. They require some bare minimum level of knowledge, but not necessarily an in depth understanding.