Agreed.

But moderately-good is also not "a sure sign that someone is trying to appear smarter than they are".

> everyone reaches the same difficulties

That is definitely false. I've had difficulties with social skills, the writing process, and knowing how to direct my attention. Some of these are so alien to other people that when I ask questions, it is not uncommon to get responses like:

* Just do the obvious thing.

* This isn't hard.

* What do you think {repetition of my question}?

* You're overthinking things.

* What the fuck is wrong with you?

The folks I've heard get discouraged from maths or science tell similar stories. Part of being good at the skill of explanation is asking questions which help you understand the other person's perspective and what their difficulties are.