He's not that wrong Dave. The Wrights certainly did their homework in so many of the areas you mention but there were a couple of other aircraft that had most of the factors before that and could have at least gotten airborne even if they may not have been succesful. The engine the Wrights developed was primitive but it did have one of the best power to weight ratios of it's day. Something that their competitors had failed to achieve.

The Wrights may have been the first to bring it all together (unless you listen to the Aussies or the Gustave Whitehead crew ) but I've occasionally wondered what would have happened in Lilienthal had had such an engine during his flying program. He had everything else even if it was only as a hang glider. A suitable small engine with enough power could easily have let his efforts take to the sky years before the Wrights.