Was hoping for a second there that they found the way not to include the serialized state (as json sitting inside the script tags) in the body of the html document (to make the page lighter), but no, that's not the case.

Anyway, it’s interesting how they separate the code for fetching data (making it a responsibility of one server) from the code for rendering data (making it a responsibility of another, Node-based, server). Which means that although they re-use the code for components, the code for data fetching logic must get duplicated.