So you're saying that using distro packages saves the sysadmin a lot of work because a lot of maintenance will be offloaded to the distro maintainers. Fair enough.

So what do you do if the specific Ruby version you need isn't packaged?

What's that I hear? Compile from source? How exactly is that any better than RVM? Every single piece of criticism you shouted against RVM applies just as much, if not MORE, to tarball compilation.