"our best java script people" I've used node.js for more than a decade now, I was there for the start of "now everyone is truly full stack"...but yes the majority of developers I've worked with have had no idea about how js etc works on the inside, no knowledge of event loop or what causes the few memory leaks possible in js.

But then again I only know because I love that shit and started out in c/embedded, c# etc. And on my own weak side I fucken suuuuck at frontend related stuff (not the design stuff at all, just...fuck you css).