This pointless way of thinking is very much like finding a more appropriate keyword for a public field, while trying to improve the methods by which VM handles big integers.
Scala is liberal.
It allows you to express yourself more elegantly. But freedom comes at a cost (this is natural!). The price is learning it, remembering it and a constant state of awareness for all the patterns it has to offer.
The speed of a compiler (think of PyPy), is a thing that can be improved at least to some extent. But very few people are willing to work on the inner structure of a language, that you doom to be inappropriate for 50% of the tasks out there.
Look at the set of various languages as a biosphere of evolving organisms. They tend to improve. If there was no demand for Scala or PHP, they wouldn't have occured in the first place.
I think the original article and the follow-up is a poorly disguised attempt at elitism, or maybe just an excellent way to challenge people.
I will say it in simplest terms possible, what really matters is how Scala handles tail-recursion, not whether it allows it. And the first point is out of reach for consideration, if you are a simple developer that may encounter 'learning difficulties'.