They could, but clearly it's vastly more complicated than just adding some jsdocs to methods or a one liner explaining "why" some code is the way it is.
Also it's not one-size fits all. There are a dozen version control systems and probably a hundred bug trackers and team management tools.
Comments
Also it's not one-size fits all. There are a dozen version control systems and probably a hundred bug trackers and team management tools.
It has a similar issue to good comments though - people don't always write good commit messages.