In a way, C can be considered an "existing platform" in much the same sense. I didn't include it in my list of examples because I really don't want to have to fight build tooling and cross-platform dependency hell in 2012 if I don't absolutely have to. With e.g. the JVM, you can get a jar from somewhere (or maven it in), and -poof- it just works, everywhere. This is a major advantage to the whole "ecosystem" point.