Languages and environments are tools. I reject the idea that they do not matter and they are all the same. The reductio ad absurdum argument is that we could all be using assembly language.
We are very interested in security so we don’t use PHP.
We wanted to leverage the massive Java ecosystem, so we didn’t use Ruby on Rails.
As a matter of taste, we like Java more than Python, so we used Grails rather than Django (but Python is a great choice in many cases because of the large Python ecosystem).