As we know, both technologies are introduced by the legends of the marketplace. Certainly, they have not created it only for sake of the developing world but they prefer to use them, for their own web applications.
Whether you are aware or not, Facebook and its related products such as Whatsapp and Instagram, work on React JS whereas Angular JS manages various Google services.
If we come out of the founder companies, there are millions of giants that use either React JS or Angular JS.
For example, Netflix, Uber, DropBox, AirPNB work on React JS whereas Upwork, Nike, Microsoft, HBO, Forbes, and Sony work on the concept of Angular JS.