Hey Ian - this is Edward, one of the co-creators of Razorframe. Thanks for your thought provoking question! Developers can certainly utilize the architecture you've described to great effect, but our solution aims to deliver a lightweight option that integrates technologies that don't normally play nice (Socket.io and clustered Node instances) but can have awesome scaling potential when they do.
By keeping all the features within a familiar environment in Node, we've experienced that development time was vastly reduced in a potential project that expected a high volume of Websocket communications. For example, the incorporation of an in-memory queue reduces the need for developers to incorporate an external piece of tech (and any new language adoption) into their Node.js projects