I think the problem here is that Scala doesn't make any choices for you. Now you're busy having to do a ton of code reviews to make sure that everyone stays within the chosen paradigm, stuff will of course slip through and bite you, and there you are with one big nice mess. Plus, it's too simple to just pull in a Java library which doesn't mesh well paradigm-wise with what you have (or a Scala library for that matter). I've done a ton of Scala and I've been left with the same conclusion as I had waaaay back with C++ - too many potential solutions, too many pitfalls and ways to make a mess. I guess I'm a person that wants to make the language make the paradigm choice for me and then I'll happily stick with that. One reason I like a language like Elixir so much - the language made the choices, it matches the problem set I work on pretty well, all the libraries look the same, life is simple, I can just write code (instead of trying to understand a moderately complex build.sbt file which basically comes with a paradigm of its own).