It seems like a tricky balance to me. I think even adults are quite bad at telling the difference between "I'm not good at this" and "this is a very hard thing". In other words, I fear the message you're suggesting would lead to the list of "things I'm good at" just being all the easy things, and "things I'm not so good at" being all the hard things. This is the classic "I'm bad at math" problem - maybe some people are, but I mostly hear it from people who have bumped up against its fundamentally difficult concepts and have drawn a premature conclusion.

I myself did this after struggling with a really good (ie. hard) chemistry class in high school. I avoided it in college until I was forced to take it, and found that I loved it. I have always regretted drawing a premature conclusion about my aptitude for chemistry.

I don't think you're really wrong, I just think it's much harder than you're making it sound, and I wonder if the cure is worse than the disease.