IME, there’s three buckets:

(a) the procedural how-to-play-the-game text is done, you’ve gone through the whole design and writing process and you’re ready to pull the trigger on publishing, and thinking or writing any more on the game is the last thing in the world you want to do

(b) you have a design goal of letting emergent play emerge, with the attendant risk that it’s not going to emerge for everyone

(c) you think you know how to talk about your game but you don’t yet because you yourself have only scratched the surface and what you think you meant isn’t actually correct

and there’s some mix of those for every project, and for one-person outfits exhaustion tends to dominate, tbqh

Also, for me at least, explaining your game is a skill that takes time to build and is different from designing your game, so. I bet there’s lot of games that think they’re explaining stuff that get to readers and don’t actually, y’know, explain stuff.

COIN has, like, a whole team that puts out the same style of game over and over, right? That’s a deep well of experience where they can make a priority of this thing that I think a lot of indie RPG publishers just can’t, even assuming they see value in it in the first place.