All JavaScript modules are singletons regardless of the format. But it's still a very common practice to export a constructor function as the module's value and

All JavaScript modules are singletons regardless of the format. But it's still a very common practice to export a constructor function as the module's value and then to instantiate new instances. No idea why that hasn't been followed with React, but I imagine that you are correct about the Facebook example. They should have put more care into making it correct rather than just making it simple to explain.