[furyofantares]

I tend to agree.

If someone has some anxiety about not understanding something, telling them it's actually pretty simple can just reinforce the framing they already have going in that maybe they're too dumb to get it.

I've found it's usually better to acknowledge that it's a little difficult or otherwise totally normal not to already know / have grasped the thing in question.

I think the intent is in the right place when saying "it's actually pretty simple" -- you want to provide optimism. The approach I like is along the lines of "this part is a little tricky, so let's break it down."