I think his Google Trends graph is way off. If you use spaces instead of dots (for example, use search terms like "angular js" instead of "angular.js" you will see a very different picture in which Angular passes Backbone early in 2013 and rises to dominance, with React following a similar trajectory below Angular, about 2 years later:
https://www.google.com/trends/explore#q=angular%20js%2C%20ba...
That graph has a better fit to my subjective memory of the popularity of these frameworks. Backbone was never so dominant, and Angular is not flat or in decline, except over the past 6-12 months its growth might be slowing with respect to React.