HTML5 Web Components - Shouldn't Be React Specific?

HTML5 web components is an HTML standard that allows you to create something that's kind of like a react component and using various library in fact you could use react within an HTML5 web component. So this got me really thinking like why aren't we building component libraries this way? I'm becoming more and more convinced that this is really the way that we should be doing things so I don't know how much impact it will have on my work. just let me know what your experience is with it or anything like it or if you think it's a great idea I'd love to hear from you.