I am not going to try and answer these, it will be idiotic but all of these articles and some of the thrust behind leaving Ruby and these articles are just driven by the wrong reasons.
However, the vast majority of "JavaScript Developers" don't know JavaScript all that well. Most haven't taken time to learn the newer features and/or syntax. Many try to write JavaScript like it's Jave or C#, or whatever else instead of using it for its' strengths. Not to mention performance implications.
Most of the time a lot of that doesn't matter. Most apps have enough performance to handle their load, and if they can scale to 4-5x the users with minimal relative extra cost, it never will. But when you do need those extra bits, it helps a lot.
I've worked on a few node/c# apps where each ms counts... getting an extra 10k requests/second on a large server, or reducing latency by 10ms is a win. Not all things are equal. One should evaluate each use case.
To each their own... I only dabbled in RoR and wasn't much into it. Ruby seems like a great next gen Perl imho, and I thought that was cool. I just didn't like the everything in the box RoR experience. I lived through the early ASP.Net and didn't want a repeat of that. I like the lego blocks approach that Node and .Net Core are taking. I try to avoid many of the bigger pieces/sets.
This isn't to hate on Python or JS engineers; just that I don't see the same jump from JS to Python/Ruby that I see in dynamic to static languages (esp static langs with manual memory management).