> "But I also do research, and I absolutely do not expect deeply technical topics like advances in aerospace engineering or gene regulation or cosmology to have "simple explanations" that I can understand."

There's a difference between explaining the entire topic and just giving you a very broad strokes approach to get you started learning the subject on your own. Nobody's having any delusions about summarizing a complex subject to a few sentences to substitute learning it the hard way, but if you can't give a very gentle explanation that can ease people in to the subject so they can get started by themselves, I would say that you don't fully understand the subject.

Also, I would add that this explanation is not universal at all. You have to be able to gauge your audience and adapt to what's most suitable.