Earlier quoted context omitted.
There's a perception in computer programming that any experience outside of the specific language, library and toolkit being used on the project is irrelevant. Or worse, an impediment; "I don't want somebody with bad habits and instincts acquired from working on now-obsolete systems". Managers really believe a kid with 3 years JavaScript experience and 1 year of Vue is as good (or better) than a senior programmer wit…
If that older Unix or C++ programmer doesn't have a strong bias against Javascript, functional programming, new es6/es7 concepts, and web appliactions in general, then sure. I see many of these types of people even on HN with biases though. Age shouldn't be used as a catch all filter, but I can see how it might be faster to screen those who have been too content to stick to their tools without catching up to industry…
You might want to check your own bias in favor of functional programming. To the more seasoned programmers this is just the latest fad. That's not to say there isn't value in it, but if you're making hiring decisions around it you've probably got your head in the clouds.