Put simply: if you’re using something like React, Vue, Svelte, whatever, then Web Components are strict overhead in terms of bundle size and runtime overhead. And when there’s impedance mismatch between the two worlds, which I hear is particularly common in React (can’t attest it personally, I don’t use React), you have to compromise on functionality or ergonomics, or else do fancier bindings, at which point why even bother with Web Components?

It will also commonly not play nicely with some more advanced aspects of the frameworks, like server-side rendering will probably suffer (depending on how exactly things are done).

In a world where React is dominant and you’re wanting to use React yourself, targeting Web Components just doesn’t make sense.

Then “headless” makes it worse. The more comprehensive implementations have a lot of overhead.