concurrently was used to run both "webpack watch" and unit tests in watch mode.
Now that we have migrated to Jest which has a great IDE support (at least in PHPStorm, which is widely used by our team), running unit tests is much easier. It was much more painful with Karma which launched a full browser.
Running tests is now easier:
"npm test -- --watch"
Running them in parallel of webpack watch leads to messy terminal output. Furthermore, it deprives us from jest's CLI which allows us to choose what we want to run, for example run all tests or only what has changed since last git commit.
The only other remaining usage is due to the angular artifact modal's mixed state: it runs a gulp task to extract translations while running webpack watch.
This will allow us to remove concurrently from everywhere except tracker. Fewer dependencies to watch and upgrade for us.