there's an implicit ownership change, from having technical writers own the documentation, to including it as part of the commit.

when things are tiny or resource constrained, the same people are doing each task regardless, but "technical writer" is a real job around documentation and manual writing, so there's at least sometimes some real decoupling between the code and outwards facing documents.

that also covers for cases where people can write code well, but who's english(or whatever the target documentation language is) is shaky at best.