Gladwell's tweakers are "skilled engineers and artisans than its competitors: resourceful and creative men [people?] who took the signature inventions of the industrial age and tweaked them—refined and perfected them, and made them work". Inventors, by contrast, are large-scale visionaries.
Who, among people who created things, exemplifies a large-scale visionary?
 A conclusion largely based on Weisberg's excellent "Creativity: Beyond the Myth of Genius" and Goldenberg's "Systematic Creativity in Business" as profiled here -- http://joshuaspodek.com/creativity