What? You're jumping to so many conclusions here, it's absurd. You're going to have to go into research for a few years if you want to get anywhere on proving that the capability of the current systems is somehow determined by the presence of StackOverflow. Sounds like you have a very tall tower of speculative assumptions about LLMs today, LLMs in the future, the evolution of the web corpus, and other big, dynamic, absolutely unknowable things.