Any developer that only knows one language is carrying around a horrible cognitive bias of how software should be written and they don't even realize it. They are dangerous, keep and eye on them, and for the love of god teach them something new.
Honestly, when I mention something like Golang or Rust or Cordova they look at me like I have 2 heads or something. Yes, I don't expect the layperson to know what those are but these are long term application developers (mostly C#) and they have never-ever heard of these things. At first I just thought it was the people I work with but I recently changed jobs and its the same thing there. I really am beginning to think that I'm an anomaly.
I know Java developers and .net developers who don't know or want to know any other language because they're not just "java" devs, they know the frameworks and have experience to build things.
If all you do is "Scripting" then sure, know a few scripting languages
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.
Sure.. some developers may not understand the implications of everything they do, but if the app has implication that impact their performance they will discover them.
Not everything needs to be over optimized, over engineered or overly complex.
As an Ops dude i find it infinitely easier to scale/manage nodejs apps than i do java.. For instance i can solve some issues by scaling out node wider across more machines than having big optimized single machine and an implication of going wider means if some things crash, the others handle it and because i go far/wide i've chosen to optimize on availability/performance in different ways than you.
I may know that a node app crashes after x days for leaky memory and deal with it because i have mesos/marathon watching alive pages and killing/restarting the container and redeploying the app or autoscaling it up and down as need be.
Replace node with anything else and you have the same problems.. we see 100's of jvms released a year.. many versions of go.. many point releases of ruby.. python.. its a never ending battle that has to be fought a lot more deeply than any one person or one developer ever can.
and lets be honest, even the best node app is building something to build the best front end so letting front end developers focus on being front end engineers and helping them solve any issues thereof to fill in the blanks is not a bad way to do business.
Expecting everyone to over optimize and over engineer and over theorize about how things should be is a huge waste of time.