[jinglebells]

I think the pattern is

    Public Web -> Reverse Proxy -> Application Server

Rather than

    Public Web -> Nginx -> Node (In his example)

You could reasonably do

    Public Web -> Node reverse proxy -> Node Application Server

It doesn't really matter if the reverse proxy is Nginx or Node or something else, it's a good pattern to insert a lightweight service at the front which can redirect the requests upstream. If you need to scale by adding new boxes or services, this can now be your load balancer.

Your reverse proxy can also handle blocking dodgy requests (Fail2Ban) or act as a lightweight static file handler, leaving your application server to do the grunt work.