Docker aside, your arguments regarding fat binaries are kinda off mark. Python has been able to package an app and all of its dependencies into a single zip file - which is what a jar file really is - since before Go and Clojure even appeared (see PEP 273). Single-file packaging in JS is also common - very much used for browser deployment.

But "let's change languages because we don't have a reliable way to copy more than one file" sounds a bit insane to me. My solution was Debian packages, not Docker, though.