It’s NOT that Apple didn't want to integrate Adobe Flash Player, Adobe could not develop an iOS version of Flash Player that was optimised enough for iOS and Adobe could not optimise the code to NOT be severe battery draining software/code on all iOS devices.
Especially smaller battery devices, like iPhones and iPods/iPod Touches.
Adobe gave up on designing ANY mobile version of Adobe Flash Player for all of the different mobile device makers starting with ending a mobile version of Adobe Flash Player for iOS, first.
Adobe was incapable of coding and optimizing a mobile Flash Player for ANY mobile platform/OS.
This had NOTNING to do with Apple other than Apple rejecting a poorly coded, battery sucking mobile version of Adobe Flash Player for any of Apple’s iOS devices.
Adobe decided, on their own, to quit trying by 2012.