I feel like there aren't a lot of use cases for custom elements (W3C web components), but a generalised component library like this is probably one of those use

I feel like there aren't a lot of use cases for custom elements (W3C web components), but a generalised component library like this is probably one of those use cases. Particularly given the ability to style shadow pseudo-elements like drop downs in a non-hacky, browser supported way. Surprised React was chosen here.