RCS archive in /etc

Well it is not a bad idea. I have worked for one place that did that. It wasn't my idea but I did not object. The reason it is done is to put critical files like nsswitch.conf, hosts, and so on under RCS control. Previous versions are then available to see how stuff changed over the years. And recent changes will be checked in by the person who made the change. That way you can ask why a change was made.