This is an interesting post, because it approaches the New Shiny Toy of web development not only from a technical angle, but from a lowercase-p political one:
Put another way, Facebook doesn't care if you use the Web, it only cares that you use Facebook.
So why release an open source Web framework at all? Because Facebook is battling Google for engineers. So you've got a big fight between two companies over which company is the coolest place to work, and both of them are companies that your grandparents love. How are you going to win this fight? One way is to have the hippest Web framework.
Basically, both Google and Facebook are desperate to find a baseball cap that they can put on backwards. Angular is Google's baseball cap. React is Facebook's.
The article also argues that Web Components are everything+ that React wants to be.