[sudodude]

I think that's just entrenchment at work. When the majority of your developers only know x languages, and one of them is always js, you tend to work by the lowest comments denominator and the tools that everyone can work with are the ones that stick.

[Turskarama]

That's true, and I also think it's a mistake.

Any decent developer can become competent with a new language in a matter of weeks, whereas making a large application with the wrong choice of language and tooling can become a maintenance nightmare. Given how difficult it is to verify JavaScript programs as "correct", its use on the server has always riled me up.