It's also an ego-threatening thing. Often the older folks or otherwise nontechnical people are socially higher status and being lectured about something that they may not understand sounds dangerous to them or they take it as being challenged by them, especially if the person explaining it is lower social status, younger, "just a kid" etc.

It's easier for them to just refuse to participate and dismiss the topic as irrelevant, than to take up the game and then perhaps be seen as "dumb".

And this state of affairs is actually quite unnatural. The natural course of things over the millennia was that older people are more experienced and can give direction and advice to the young ones. Sure, this is still true in some "soft" topics, but the generational gap in understanding how the modern world works has never been so large.