I don't think we should tell a person at age 15 or 16 that they have a limit on what they can accomplish. You can train a person with a strong, general education to weld just as easily as you can train a person with a more limited education who is two years younger. However, when the person spent the last two years of high school learning to weld instead of learning English, math, science, and civics, it's much harder for them to learn enough to start their own business, go into politics, or change their careers radically.