Products rarely win because of technical merits. Products win with marketing. Technical merits can add another layer to the marketing but without facebook's brand people would still be on angular.
It's unclear to me that Facebook's 'brand' is superior to Google. Google has plenty of popular, successful open source projects. If Facebook's brand was all that was needed for it to crush Google, wouldn't Pytorch be crushing Tensorflow right now?
We are talking about a different time and different market. Google had the top brand overall back then but just in terms of frontend frameworks their brand became mud and no one trusted them after they spent the last year or two moving into angularjs and now they needed to rewrite everything. So they rewrote what they had in React instead of AngularJS. Facebook had the more trusted brand over Google and other frameworks.
