You are welcome to believe the myths, but the consensus of military historians is that Dieppe was a debacle and nothing much was learned. This consensus is best expressed by perhaps the most respected Canadian military historian (and former Canadian Army veteran, Jack Granatstein:

"There was heavy bombing, though it was not hugely successful in destroying beach defences. There was massive naval gun support, which was successful. There were better landing craft and specialized armoured vehicles, and the assault troops were far better trained. All of those things would likely have happened even without the Dieppe raid."

"Some lessons were learned, but most of them were lessons that had been mastered before. Many of them had been taught at staff colleges for decades. Most of them were simple common sense."
Dieppe: A Colossal Blunder
http://www.canadashistory.ca/Explore/Military-War/Dieppe-A-Colossal-Blunder