If everyone agreed with this teacher there would be no mathematicians or classical musicians. Standard school curriculum (in the U.S. anyway) is incapable of instilling these skills (without supplementation).

Actually, I don't know this to be true. I just suspect it. Can anyone provide an example that refutes me? A brilliant individual who went through a regular HS and then got a PhD in math at MIT without the parents enrolling him/her in math camps or volunteering to help with math competition prep or otherwise pushing for more challenge. In other words, WITHOUT parents who "focus on the "gifted" side and want extension and push and whinge and carry on and are general PITA"?

Just for the record - my kids are really happy kids and a pleasure to be around. ALthough I must admit - they aren't as smart as many of the children I read about here!