[rk06]

What exactly virtualenv adds to table that justifies it?

I have used c#, and javascript. And not felt any issues by lack of virtualenv.

I know python need it because otherwise it does not support project level modules. But that is a python only problem

[pizza]

Sure, just for managing the project-level language versions + project-level library dependencies. Doesn’t need to be exactly venv, but venv has proven simple enough to use that it tends to reduce headaches, rather than add more, in my experience.

The reason is that pip/most package managers have a default to install a package globally. Which can be annoying especially for noobs.