Are you sure? I'm not familiar with the PHP.net architecture, and there may be less gains from how PHP has traditionally tied itself as a module to web servers in the past, but Rails (and any number of other dynamic language frameworks) are actually web servers implemented in that language, with an optional separate web server such as NGINX or Apache you can run in front to handle the stuff they aren't as good at (static file serving, etc).
Now, that is a framework, and not the language proper, but I wouldn't be all that surprised to find python.org running on top of a Python framework.
"NOTE: Some of our maintainers prefer to use web servers other than Apache, such as Nginx. While this is permitted (as long as everything ultimately works as directed), we do not officially support these setups at this time"