As the post notes, the JS world is moving away from the side-effect heavy code that motivates Object.observer.
It may well be that Object.observer was the wrong level of granularity, and I agree that language specs should evolve cautiously.
That said, I think it is far too early to make generalisations as broad your statement above. React-style development is still a tiny fraction of overall web development, and React itself isn't even at version 1.0 yet and IMHO still has significant fundamental architectural concerns that haven't been fully explored yet. It promotes some interesting ideas, and I'm glad someone with the profile of Facebook is challenging assumptions, but in turn reasonable people could challenge a lot of the ideas coming out of the React team and we're still far from understanding the long-term trade-offs of that style of building for the web.
It may well be that Object.observer was the wrong level of granularity, and I agree that language specs should evolve cautiously.
That said, I think it is far too early to make generalisations as broad your statement above. React-style development is still a tiny fraction of overall web development, and React itself isn't even at version 1.0 yet and IMHO still has significant fundamental architectural concerns that haven't been fully explored yet. It promotes some interesting ideas, and I'm glad someone with the profile of Facebook is challenging assumptions, but in turn reasonable people could challenge a lot of the ideas coming out of the React team and we're still far from understanding the long-term trade-offs of that style of building for the web.