It's not about the language their implementation is written in (although many people find MLs and Lisps to make compilers and interpreters much easier to implem

It's not about the language their implementation is written in (although many people find MLs and Lisps to make compilers and interpreters much easier to implement), it's about the machine that their implementation targets. The JVM imposes many restrictions on and makes many assumptions about the behavior of client languages as a direct result from being built to host Java. I have no doubt that the CLR is similar. Javascript and Ruby are not typically compilation targets, bar things like ClojureScript.