In theory, you can completely statically render everything. In practice, every static site I've seen built with React also uses dynamic client-side components,

In theory, you can completely statically render everything. In practice, every static site I've seen built with React also uses dynamic client-side components, either as a prerendering mechanism, or because there are dynamic toggles and things on the site that are easiest to build as React components. This usually means that a lot of excess Javascript gets loaded on the client that isn't usually necessary. The islands/RSC work seems to offer some improvements to this, but most of these websites still include a full copy of React on the page to essentially do what the speculation rules API and a `<dialog>` element could do just as easily.