> The amount of knowledge to be good at all of this far surpasses the "oh, they only know javascript" naivety that I hear from other developers.
No, that's not it at all. I am friends with front end guys and I'm aware at how much work it takes to just keep up with and be good at the framework du jour, Backbone or Angular or React (then Flux, then Redux) and whatever's next from there.
Being good at markup and layout, and being good at a front-end framework, are not skills that are direct analogues to systems-level issues that plague Node.
For example, Node LTS's Buffer() uses UInt8Array on the browser, but a malloc() on the server side that may return insecure memory with leaked information from other parts of the process. libuv's event system is written in C. Socket programming on -nix is nothing like using a WebSocket library in Chrome, and the front-end has no concept of filesystems outside of localStorage or limited WebSQL use. When was the last time a browser had you deal with malloc()?
How many front-end developers understand the performance of writing files to disk with different filesystems, master-slave or master-master replication of databases, building solid server-side deployment workflows, securing their code and their servers from all the things that can go wrong? This skillset generally doesn't exist; it's abstracted away by the Chromium sandbox, or the interpreter. Front-end generally does not require knowledge of the principles of the underlying operating system and architecture to get the job done.
On the backend, all of these problems become apparent. It takes a different way of thinking, and a different understanding of a computer system. My original comment to rdtsc is just that -- a "JavaScript" developer that works on front-end tech only doesn't have an adequate idea of how these things work to build good server-side architectures, and Node.js is not the tool to use for those types of things.
Frankly, if they only know JS, they haven't touched these things at all. Outside of Node and Electron, virtually nothing on a system outside of a browser is written in JS, so you wouldn't have picked up these systems skills in JavaScript.