Streaming section by section of a frontend sounds like a troubleshooting nightmare. Users expect an interactive experience with a website. That means JavaScript. Anything else is going to be more complex.
When I'm in a browser, 99% of the time I expect the page to have what I'm looking for. I rarely care if its interactive. In fact, the more interactive it is, the less enjoyable the experience is. This holds even firmer when I'm on a desktop.
With webpages, any delays make intuitive sense and are accepted by the user. With an interactive web app, the web app gets blamed for any delays or latency because there is no full-page refresh.