在一个端口上使用单个应用程序的节点应用程序使用代理服务器（如node-http-proxy）有什么意义？

I'm exploring using the node-http-proxy proxy server so that I can have our proxy server on port 80 forward requests to our app server on port 8000. However, I'm a little confused as to why this is a good idea, and what exactly this set up would protect against security-wise. proxy s