I think a Web Component is meant to be like a <div/>. It's one of the pieces that you render on the server. That way the client is dumb and just implements a design language in Web Components/JS, and the server sends commands to lay them out with data already bound.

I don't think that was the objetive of Web Components at all but to really create open standards around what React started a long time ago. Server-side rendering is not going away ever, there will always be a way to optimize things and to do tree-shaking and all so don't think that a new technology replaces everything else the rest of the eco-system will still remain with a clear purpose. You can do a small little project without builds and all but every "real" project will still need a build process in the end this concept was inherited from Continuous Integration and it's not going away.