Did you read that? It does not support your notion that the plan9 community thinks programming is the way to customize software. It shows that the plan9 community thinks you shouldn't do those things, at all. They are not missing because you should edit the code to change them, they are missing because they should never exist.
Are two totally separate things and you are painting them both with the suckless brush. The plan9 community is nothing like that at all.