This is a pretty interesting concept. Experts often forget (at least consciously) the details of what they once learned since their knowledge has become ingrained and automatic, especially when technique has become muscle memory. I saw a concise description of this phenomenon recently in this video
(from pop philosophy guru Manson, but still valid).
As you say, the theory suggests that some coaches might be experts at a technique and still be incapable of describing the nuances of said technique to students. A coach that can perform and accurately describe those nuances would be the thoughtful type that is interested in why they know what they 'know.'
As an adult learner picking up the sport after 40, I'm still unsure if whether I'll develop faster understanding the ins-and-outs of a technique from more descriptive coaching, or if this sort of overthinking might get in the way of a more 'natural' skill acquisition.
The solution I'm trying out, which I pulled from a Huberman lab podcast, is to only focus on one singular aspect of a given technique during one training session. So for FH loop, some sessions I'll only concentrate on brushing contact, some I will focus on finishing with a proper salute, some on footwork, some on weight transfer, etc. There are apparently some studies that suggest that this focused attention on one aspect of a movement results in accelerated skill acquisition compared to the more unfocused 'natural' training. If anyone is interested in this concept, you can hear it described in this video: