There's no sense in rationalizing with folks who want to quantify intelligence in the first place. They're chasing statistical phantoms. Even if we take a generous view of what they said and interpret it to mean that brain development finalizes in the mid-teens, it's still a completely myopic view of what it means to be "smart."
Have you played sports? Most sports fans and players know that determining which players are better than others in their domain is an endless debate that is in the end, still completely subjective. The only thing approaching objectivity are events like the Olympics, parts of which are still subjectively scored.. on top of that, for the ones that aren’t, better performance on a particular day in a particular event doesn’t mean one is a better athlete. To summarize: better performance at a combine 40 yard dash means nothing when it comes to performance in a game.
