The negative hype around flash after apple categorically rejected them for inclusion in iOS safari has made flash look like a non-peforming platform in the eyes of everybody.
This opinion is not totally untrue though. I tried writing an app using Flex for iOS and quickly realized it doesn't perform as well since it can't leverage multi-threading of iOS (since it's a single threaded runtime)
Because at one point Apple started banning all use of virtual machines and external runtime, including Air and it has gotten a lot of publicity. Since then they have reverted their policy but a lot of people who didn't plan to use Air in the first place continued to hold on to the old info. One of our my apps uses Air so I have been following this very closely.