[snarf21]

I would say (largely) even good designers don't write great rulebooks. It is a total different skill set. The best analogy is that Publishers are to Rulebooks what Software Releases are to QA. It is always left to the end and rushed out the door. There is an assumption that between social media and BGG and How to Play videos that people will figure it out.

[vintermann]

Well, there's two steps. To write a good rulebook, you need good rules first. You need to really think about it like a programmer, in terms of procedures, invariants, completeness etc. So that when you, when you play your own game, you don't constantly run into rules questions that you have to stop and settle. If you do have clear and consistent rules in your head for your own game, then writing a good manual is just craftmansship, that you can even get in a professional technical writer to do for you.

But as all programmers know, your mental model of your program is probably full of holes and dubious logic. And so it will often be for board games. Then a technical writer can't save it.