I believe that the relative size of one library vs another (even outside of the reality of caching CDNs) is an unhelpful distraction from the bigger discussion around who should consider using which tools for which jobs, when.
The applications I'm working on are typically for people with usable broadband connections. If you build your site/app correctly, the pictures that are embedded in your content are often bigger than any of the libraries you could choose. However, it's the general responsiveness of your experience that people will judge your speed or "nativeness" by.
I do agree that the examples on the site are somewhat outdated, but the fact remains that there are a lot of nice things to say about that dang left column, with its predictable, intuitive and impressively terse invocations.
The examples in the site already look quite outdated. We now have `fetch()`, `.attachEvent` is all but dead, plus all the ES6 features like arrow functions, destructuring, spread... and reactive UI means you'll rarely, if ever, need to call DOM tree modifying methods yourself.
The best part, "Reactive UI" being a paradigm, you have many other options besides React+JSX, for example https://github.com/jorgebucaran/hyperapp. At a fraction of the size of jQuery, which one is the 'monster'?