I don’t know who “Chris” is, but his (her?) comment – on this post at Marginal Revolution by Tyler Cowen – offers information that is too often overlooked and insight that is too seldom displayed:
Jet aircraft were developed prior to the war by Britain’s Frank Whittle and Germany’s Hans von Ohain in the 1930s. Working turbojets and jet engines had already been built by the time war began as well as several prototypes actually flying. Britain was probably the world leader in jet engine technology at that time although Germany was close.
Britain and the United States both correctly predicted that the design and mass production of jet warplanes would come too late to have a decisive impact on the war, so the decision was to concentrate on producing conventional aircraft that could be deployed during the time frame of the war. Germany however diverted huge amount of resources to bring jet aircraft into production sooner; something most historians consider to be a blunder. Germany would have been better off with more conventional aircraft. The Me-262 looks great, but had no impact on the war when it was introduced in April 1944. The Allied jets came out shortly thereafter. British Gloster Meteor was introduced several months later in July 1944, and the American P-80 Shooting Star in 1945.
At best, the war lead to a quicker production of existing technology by several years. However, in terms of development of new technology, there might have been no impact at all. Maybe no P-80s being mass produced, but a single prototype that looks just like it. Perhaps even the opposite could happen – without the need to produce thousands of conventional B-24s, P-51s, etc., immediately perhaps the resources would have existed to introduce jet aircraft much sooner.
Most of the “wonder weapons” and “new technologies” that appeared in World War II were of a similar nature – they were concepts and technology known in the 1930s, but simply not put into production because there was no need. Wars tend to accelerate the time technology is put into production, but kills the long term research for future development. There are only so many engineers and scientists to go around so if they’re working on immediate war time applications, they aren’t developing new concepts.