[dehrmann]

This is usually a smell that the person is competent at what they do, but doesn't know what's going on under the hood. Funny enough, I'd rather work with someone who doesn't know the specific technology, but knows what the language was built on top of, because they'll have a better intuition for how it actually works and be able to learn it relatively quickly.

[II-V-I]

I'd rather work with someone like that, too. All is well and good when one can crank out React components, but if that same person doesn't know how to find, for example, the tag name of a element from an event handler, a little red flag goes up for me, and as you said, probably doesn't know a great deal about what's going on under the hood.