React is for scale, just not the way you think: React is designed to allow lots of journeyman web developers implement parts of a web page together, such that every component can work by itself and that one component's failure does not break other components, allowing pages consisting of multiple components that may have been dynamically assembled from dozens of different authors to work together.

This seems to be a central point that the "I can just do this in CSS/HTML/JS" crowd continually misses. It really doesn't matter that you can do it... It matters that you can dynamically compose your work with hundreds of other people.

IMHO, most expert devs don't meet this bar with pure web tech, but unlike the W3C, I don't blame the webdev for poorly composing solutions, I blame the web standards themselves for poorly defined compositional properties.

But the platform has at least risen to the level where we can define its behavior ourselves. So I think it's healthy for other sources to push innovation because React upped the ante for Web Components and Web Assembly. The W3C will eventually understand the need for composition and isolation at scale, but they would have taken a lot longer to recognize the use-case without a competing concept like React.