> But that would not explain NodeJS, JavaScript for embedded microcontrollers, and so many more.

I'm only going to address NodeJS because I think that niche projects that target niche workloads are just unrelated.

I believe it does explain NodeJS. The idea is simple - your frontend engineers can own your edge services/ APIs. They're already heavily invested in JS and, at least at one point, there was a theory that unifying languages across frontend + edge made sense for other reasons.

Some people really just learn one language.