I don’t think this comparison is correct. You concluded that not much has changed in 15 years, but you are not comparing 15-year-old idiomatic Backbone code with modern React. Instead, you are comparing modern Backbone code with modern React.

You could make a similar comparison between Kotlin and Java and reach the same conclusion. However, Java has evolved significantly over the past 15 years, and most of Kotlin’s features are now also available in Java.