While true that some languages (and supporting open source modules) are better at certain tasks than other, I believe the real reason people want "one language to rule them all" is reduce the loss in productivity due to context switching between languages.
Try going back and forth between langauges when you have an app in Java/Obj-C, high performance native code in C++, a backend server written in python/php and an admin dashboard written in Javascript.
> Now I can have a production-ready Node.js stack after 5 minutes on StackOverflow
The only 5 minute task that is likely to result in an actual "production ready" environment, is making/buying a cup of coffee.
This sums up my beef with what appears to be a reasonably popular interpretation of the term "dev ops".
People always claim that developers should have more hands-on involvement in managing servers.
In theory that's fine, but the problem is, they generally don't tend to appreciate that sysadmin/server management/call-it-what-you-will is not just 2 lines of shell commands copy-pasted from stack overflow.