I tend to agree with you, we should not undersell people and their ability to access and make sense of complex ideas.

The problem is, good communication does also require simplification, and doing that correctly without causing more confusion is difficult.

I think there should be layered communication, (at least on important things), where there are easy accessible formats for people who do not have the time, brain power or energy to look deeper, and more thorough explanations where people can be walked through the complexity, even when they might not have the background to fully grasp all nuance involved.

Mixing between these two causes a lot of troubles, because only presenting 'easy answers' will make people feel lied to, and only 'complex answers' tend to be to hard a burden to put on many people and hinder effective coordination.

I do not share your experience that 'experts' do not believe 'ordinary' people are capable, I much rather think that experts/institutions want to make people's lives easier, and not always succeeding in communicating this best.