Would an experienced Java developer that has never touched JavaScript before know how to use JavaScript well enough to use it in a professional application without having to learn/revise a lot of things?
Would an experienced JavaScript developer that has never touched Java before know how to use Java well enough to use it in a professional application without having to learn/revise a lot of things?
No and No - They are like car and carpet. Unlike something like C and C++ or JavaScript and TypeScript that you can easily adapt to in a relatively small amount of time, Java and JavaScript serve completely different use cases and require significantly different skillsets.
I feel like this misses the point of why people say Linux is for programmers pretty hard. It is not really about writing code, just about being tech-savvy and properly knowing your way around computers, which OP may as well know better than a lot of programmers.
Cherry-picking a lot, but I cannot imagine saying this to a normal biased person would make them any more likely to consider Linux:
It is important to recognize it still demands a lot more technical aptitude to find and understand information about how it works, how to it set up and how to customize compared to Windows or Mac, which come preinstalled and hold your hand through the setup process.
It isn't anything out of this world, but does require more effort than proprietary commercial software and we shouldn't pretend otherwise. Great article besides that though, and this wouldn't really be an issue if it weren't for that being the headline.