React's learning curve is tiny compared to Angular. With React, you need to understand the component API, which consists of about 5 methods that one uses regularly, and the top level API, which consists of 2 (or just 1 if you use ES6 class syntax to create components). And as the article points out, it's just JavaScript.
I had the complete opposite reaction. I learned a bit of React through a rails + react tutorial and I was lost pretty much the entire time. Having to write HTML using either JSX or the ReactDOM syntax was a complete nightmare. Granted the testing options of both beat out angular, but even at a surface level React just wasn't appealing.
Can you expand on this? I find writing JSX to be a breeze. JSX is basically HTML with a few small tweaks (e.g., for => htmlFor, class => className). If you use a linter, it will catch those mistakes for you while you're learning.