I'm not saying Ruby on Rails is the best backend framework (I don't use it anymore), but when it came around everybody understood that it was getting something right. It popularized a new model for server-side web development that all other communities started to follow and improve. When it came out, most developers who were already working with the web could see that it would be very useful, it solved real-world problems they had, it just made sense.
This is much less clear with JavaScript frameworks. They usually have a tough learning curve and the benefits are not always coming as expected. So people keep trying to find a model that works well.