Examples like this bug me. The React example is using a high level abstraction, the web component is directly using the API. A more accurate example would show how those React calls eventually boil down to document.createElement()
I don’t think the Web Components API was meant to be used directly all the time. You can use a framework like StencilJS:
I don't know many (any?) people who are greenfielding just-JavaScript, though. If you're using JavaScript in anger, you should probably be using TypeScript, and now you've got a build step regardless.
Which is not a bad thing. Incremental builds have gotten much better and much easier to deal with.
There are still some frameworks that let you write fancy front-ends without a build-step and associated tooling. And there's people like me who prefer those since they meet our needs.
I use web components in a small project where I don't want a build step (it's plain HTML and I just use web components for re-usability instead of copy+pasting mark-up).
Here's legacy React's like_button.js, without JSX, from their old documentation:
Here's the equivalent using the Web Components specification[1]: The React API is slightly nicer to use, especially with JSX.[1]: https://github.com/andrewmcwatters/custom-elements