To be frank, I think in large part this is due to React.
I'm not an authority in this area, but I seem to recall that because React uses a synthetic event system, it won't interoperate with Web Component bindings and emitted events. (I know React doesn't work well with Webcomponents, the part I'm unsure of is whether it's specifically due to this).
React also doesn't have an easy means of turning React components into Web Components for publishing and consuming. (Preact does though, they put a lot of work into it).
Svelte, Vue, and (I believe) Angular can all emit web components.
In Vue, you can use the framework's standard data-binding and event capture syntax to interact with custom web components. You wouldn't be able to tell the difference between a Vue component and a Web Component you imported from a package.
(I can't speak for Angular, maybe someone could chime in here.)
To me, it represents a huge failure on the part of the developer community not to make publishing web components the standard.
It seems silly to write a wildly popular component/component-library, and vendor-lock it to a single framework. Why not just publish a web component version as well?
https://cli.vuejs.org/guide/build-targets.html#web-component
https://preactjs.com/guide/v10/web-components/
https://dev.to/silvio/how-to-create-a-web-components-in-svel...
https://angular.io/guide/elements