Ah, here is where it gets actionable for us scouters. I agree completely.
Advancement can become "scouting materialism", in the sense that you're talking about. If scouts weigh their own worth as a human being based on their advancement, something's not quite right, but we're the right folks to look for that and correct as necessary. If nothing else, if others around us don't see the problem, we can just straight up point out the misunderstanding to the scout. Their essential worth as a human being does not depend on scout rank or advancement at all, and never did. Just being together an