RubyMine 3.0 and RVM

Continuing on my journey of trying to learn Ruby/Rails 11 days before X-mas, I decided to test drive RubyMine from JetBrains and initially it had an issue with detecting rubies (ruby interpreters) I had installed via RVM.  I quick posting to the JetBrains's forum resolved the issue, but it did make me think just what are the benefits of using RVM as opposed to just installing Ruby and Rails system wide...