From the perspective of a stodgy enterprise java developer, I don't find the 'common language' argument compelling. The advantage is limited to common syntax and runtime model of the javascript/node environment. However, the problem space is quite different: on the client the task is user interaction, user interface design, translating user requests into backend data requests which can block and call back. On the server side, ACID data persistence and business logic including backend service integration. I think these problems create a greater separation of client and server developers than the programming language. Someone very good at user interface design may not have the chops for ACID data persistence, and vice versa, EVEN IF the programming language and runtime model are the same. After 15 years programming java, I picked up javascript rather quickly. I can do the transactional business logic development in jee with cross concerns of security and concurrency, but if I used javascript to write a user interface, I need more learning beyond javascript. I think 'full stack' developers are quite rare. Declaring oneself as such would be a mistake if one's ground to say so is only the programming language is common to both by happenstance.