This is so true. It's like the old truism about how the way to really truly learn something is to have to explain it to someone else. Literally just going through the process of articulating something, just putting it into words, is an amazing tool for revealing all of the missing pieces and inconsistencies that would otherwise be implicit.

Until you put something into words, one way or another, then it's just a fuzzy blob of assumptions and halfway articulated thoughts. The better someone is at writing, the better they're able to articulate their thoughts, even if it's just to themselves.