What you’re defining is the difference between “smart leaders” and “good leaders”, mistakenly conflating “smart” with “good” which is precisely the parent’s point. You can have leaders who are good and smart, and you can have smart leaders who not good at leading.

Just to complete the quadrant, there are also dumb leaders who are good at leading (will usually still do quite well) and dumb leaders who are also not good at leading (usually does not end very well, IMO this is where middle management tyrants come from). Even though I'd wish it were not so, smartness is correlated to success in the same way that hard work is: it helps, but you still need a lot of luck as well.