[fabian2k]

I think for many cases it is fair to make the assumption that you're staying roughly within the same kind of application. So if your team previously did web applications you won't suddenly do embedded stuff or high-frequency trading. And within such an area, there aren't enough differences between languages to overcome the drawback of learning a new one.

[pdimitar]

There is plenty of difference in Web backends. F.ex. Elixir, Golang, Rust make parallelism much easier and they scale better on a single host (which is what at least 95% of all startups ever will need).