It was created for people without JS experience, specifically Java devs that moved from back end to front end teams to write webapps. Things have since moved on and we're bringing the coding style, among other things, more inline with new practices.
The tooling itself is Java since a lot of Caplin's customers still have't adopted Node, in fact some of their ops departments are completely opposed to it, and just because it isn't written in the same language as your front end code does't mean the tooling and principles are any less valid or useful.