Author here. I think it's a combination of things. Node came onto the scene, and the hype hasn't really let up yet.
In addition, ZIRP made hiring cheap, and JS was ubiquitous -- bootcamps pushed it, marketing and trends pushed it. The choice was obvious, even it it wasn't great. Go also emerged and proved to actually be great. Meanwhile, Rails was seen as boring and slow (though YJIT has drastically improved that!)
But ZIRP is over. Simple, boring tools are coming back, and complexity is now seen for what it is -- risk.
In a world where efficiency matters again, imo, Rails will see a renaissance.
