[Scarblac]

This works for small programs you write on your own. Even then, the kind of problems you even try to solve in Matlab are different from the ones you try to solve in JavaScript.

But in business, you often program within some framework (which makes some things easy, other things hard), glue together tons of open source libraries (what's available in different languages differs a lot), and you work on huge codebases in teams (and different languages get in your way in different ways).