Actually not true. If you love making software you will probably use Scala without its esoteric features (for the better, imho) and you have a powerful and useful tool, yet very pleasant to work with.
The point I was trying to make is that it does not have to be cryptic at all!
I worked on a play app where it was really easy to go around and even JS front-end developers made small contributions.
Maybe some teams need to set up rules, or do more code reviews idk.
Every teams ends up with different subset of features through. When you take over after different team with different culture, the deciphering problem gets back.
Also, through I did not seen it in Scala but in different language, the part of coding I personally enjoy the least was the prolonged fight over which features are going to be used with code reviews being primary tool to force other team members into submission. Seriously, I like following team standards, but new rules suddenly appearing during code review were pretty annoying - giving me a choice between not meeting deadline and following other dude random opinions whether I agree with them or not.