It looks like the backend is "dumb", and doesn't handle persistence (as it's not really needed), so using node allows the OP to simply store session state for c

It looks like the backend is "dumb", and doesn't handle persistence (as it's not really needed), so using node allows the OP to simply store session state for clients on the stack as a global variable, so the server is completely independent and doesn't rely on any additional infrastructure. Most other backend techs (PHP, Ruby, most Python) simply handle the Request/Response cycle, with memory being cleared and allocated each time. Other web techs can do this, but node madebit easy " out of the box".