But if you have large apps with multiple Ruby versions then dealing with rvmrc...
Why on earth would you do that?
You have an app with multiple Ruby versions?
Yes. I take it you've never worked at an enterprise company before ?
Every time a new developer comes on board they just love to add new technology X and then in the years to come other developers add Y and so on. Of course there are developers who have to manage this.
Enterprise company? Ha. Just try dealing with three different decade-old JVM versions once. You'll pray for bundler.
But if you have large apps with multiple Ruby versions then dealing with rvmrc, bundler and gem incompatibilities is a nightmare.
Java's forward compatibility is a lot more robust.