[pmontra]

There is another more detailed answer but the first thing you learn when programming with Ruby, Node and Python is that you can't rely on the distributions.

I give examples with Ruby: distributions have ridiculously out of date versions of the interpreter and sometimes they don't have what you need at all.

Suppose I want jruby on a Ubuntu 12.04 LTS

    $ apt-cache show jruby
    ...
    Version: 1.5.6-2
    ...

According to "rvm list remote" jruby is at version jruby-9.0.5.0 (9 followed 1.7).

Now suppose I want mruby.

    $ apt-cache show mruby
    N: Unable to locate package mruby
    E: No packages found

Ops!

Now, is this because the distributions don't have time to package and update interpreters and a zillion of gems or because their authors are not collaborative enough? This enters the realm of the other answer. Given the current status the only solution is bypassing the distros completely. I use them only for the OS, I get dev tools from their own repositories, whatever they are.