"Gifted" is defined as those scoring above a certain percentile on a set of evaluations. So there is little doubt, IMHO, that there indeed is such a think as "gifted".
There are professional football players who took up the game late, so didn't excel in jr. high, high school, etc. Does that mean there's no such thing as a great high school football player? Of course not.
The process we have may not identify every single high achieving person. It's a statistical certainty that there are very high IQ children living in the backwaters of 3rd world countries that we haven't identified. That doesn't mean that those we have identified don't exist.
There are also many academies that teach children in various ways. I've yet to see one that churns out every single student with a "gifted" score on standardized tests. Yes, you can maximize everyone's capability. But pretty much my definition, not everyone can be in the top 2%, 5%, whatever cutoff you use (unless you're at Lake Wobegone)
