The state of affairs with Ruby OS integration is pretty poor.
It's not a problem for me because Ruby is my bread and butter, so of course I have rvm (or rbenv) installed at all times. But as I user I think it's unacceptable to have to do a manual installation just to run extremely simple programs. It'd be nice if the community were more responsive to fixing the problems faced by the package manager maintainers.
IMO, it'd also be nicer if package manager maintainers worked harder to not break the default assumptions of Ruby developers.
All of the RubyGems developers are volunteers—as are most (if not all) of the various package manager maintainers. The way that Debian broke Ruby in the past (I don't know if it still does, but I have heard reports that it's better)…was unconscionable. (This mostly because Debian tried to treat RubyGems like C-based libraries, which are hard to have multiple usable versions of; RubyGems was based on the idea that you might need multiple usable versions of a package around.)
Rather than repos providing out of date Rubies and gems, wouldn't it make sense to solve the conflict between the two approaches in just one place, and make nice reliable RVM packages for everyone to use if they need Ruby?