I think the problem with the article is that it is just looking at components (as a developer I have wanted the encapsulation this methodology brings), whereas react offers more than that - the virtual DOM, for example.
Ah, yes - within the same applications, components are often re-used. Still, it's a stretch to say code re-use is the main reason people are using React. Rather, its advantage lies in its composability and how easy it makes it to separate view logic from other logic. And probably a few other reasons that other people would name as well; in any case, it's not just the ability to re-use components, and an alternative only providing that part is not going to replace React in my applications any time soon.
I reuse components in different applications. There are also popular third-party components (and even whole libraries) to be found on github and elsewhere.
I don't think web components will replace react, simply because they do different things. You can write web components in react which gives you the best of both worlds.
