It's nothing to do with nastiness from older folk IMO. Perhaps it's more that it's older folk that tend to frequent forums.
Maybe there's an unwillingness to change as we get older though. Partly because we give up learning new tricks. And partly because we're happy with the tricks we already have. They're hard learnt from life's ups and downs. And, crucially, we know they work for us.
Relating this back to photography I'd say this. After 40 years starting with film I've always had an interest in theory. I want to learn every nuance of my camera for example. But I'm not a technical expert, let alone a scientist or electrical engineer. I just want to master nailing the shots I need, and I do.
Lat time I looked, you don't need to be a scientist or electrical engineer to be an amazing photographer. In fact, many amazing photographers don't give a monkeys about theory, let alone frequent forums.
Science and theory is great. We all learn something new every day. We evolve accordingly.
BUT what we don't tend to do is change something that works for us simply because somebody else implies that we're daft if we don't.
We make informed decisions instead.
Absorbing facts that you didn't know before is great. With age and wisdom you are increasingly equipped to adopt or ignore new knowledge. Depending on your own needs and acquired wisdom.