For the purposes of official documentation, it might be better to not use some of the casual comments in this discussion.
For example, it’s not that it doesn’t actually write files other than gradle-wrapper.properties, but that it writes the versions from the current version, not the updated version. They look untouched, but technically the bytes were still written.
Effectively, you could be getting an update every time you update versions, just the JAR would be updated to your n-1 version while the gradle-wrapper.properties is updated to n.