I don't think anyone's getting confused but I do think that having four different ways to write essentially the same thing can lead to inconsistent code. And when you have a large project with lots of people working on the same code and with people coming and going all the time, consistency matters.

Scala has some great ideas, but it's so easy to abuse it. I know, I know, you can shoot yourself in the foot with any language. But there are languages that have several safety mechanisms you need to circumvent in order to be able to shoot yourself in the foot, and then there are those that give you a gun and a book called "How to shoot yourself in the foot".