I don't think you understand how that metaphor works... are you trying to say that every problem is the same and developers choose wildly different tools for the job?
Maybe somebody should coin a new "Law". Something like, "The fact that something can (and apparently therefore will) be programmed in JavaScript doesn't mean that it will be (useful|performant|efficient|high-quality)."
I happen to agree with him. Just because something can be written in JavaScript doesn't make it a "good idea" for certain domains.
"when all you have is a hammer everything looks like a nail"
vs
"Look, everything looks like a nail! Let's use that screwdriver over there as a hammer."
So despite having multiple tools, everything still looks like a nail. Think of your typical boring webapp development that most of us have done a thousand times.
Rather than use the same tools you always have and are familiar/bored to death with it's often quite tempting to use something else to help keep things interesting while hoping that it might actually end up being better than what you've used in the past. Chances are it's not. but that's what learning is all about.