The AngularJS team is. Angular was quickly becoming the de facto standard for building web apps (right or wrong) but then they came out with Angular2 which was a complete rewrite with no upgrade path (at the time of the announcement at least). The reaction from the development community was swift and angry. Why would anyone write an Angular 1.x app that was going to be deprecated in less than a year? Writing anything serious in the 2.x codebase was a no go since it was still in the alpha stages. Everyone started looking around for something new. Enter React. The learning curve was way smaller than Angular 1.x and it whomps the competition in terms of performance and scalability.
Now don't get me wrong, I love me some Angular and think the 2.0 is a massive improvement. Its still in beta though so its not a good fit for most projects yet. I am just saying that I saw React explode in popularity right after that.