That's the real substance of the post right there. It's a valid expression of the author's experience. But it's irrelevant to people who know they need React and know how to use it appropriately.
I've been building websites since 1996, using HTML, JavaScript and CSS right from those early days.
I always found it frustrating for building rich web applications, or even "plain" websites with any significant amount of interactive functionality, and I made several attempts at building frameworks of my own to make it faster and simpler.
jQuery, Prototype, ExtJS/Sencha, Backbone.js and Angular all seemed promising, but none took enough of the pain away.
Since I started using React about 4 years ago, I've found building rich web applications a joyful experience for the first time in my career.
To be clear, I'm not using it for tasks where plain HTML/JS/CSS are adequate for the job. When I build basic info webpages, I just use plain HTML/JS/CSS, with maybe a bit of jQuery. It's fine.
But a lot of my work is on sites/applications where many data entities need to be updated in many different places across a view or the whole app frequently and quickly (notably, apps that display live weather/environment/crop data for farmers and researchers), and React with Redux makes it very simple to do, with the app still being lightweight and fast to load and very responsive to user interaction.
And it's a nice bonus that I can re-use a lot of the code for native-ish mobile apps using React Native.
But I only knew that React was useful for me, and learned how to use it, because I had a pre-existing need and many years of frustration using frameworks/libraries that didn't tick the boxes.
If the author isn't building products that would actually benefit from the introduction of React, then it's unsurprising that they don't see the benefit or find it easy to learn.