I 99.9% agree with you, and of course this is more of a "theory" thing rather then something that should be applied "in practice".
But this is the first time that I'm approaching shipping a game "for real", and realizing just how much work there is to do even at a stage where I can confidently say "there's just content missing now", can be daunting.
Just wanted to share the feeling that saying "Oh wow, I'm _mostly_ done" doesn't mean _at all_ that you're ready to ship :)