And then you can cache it. Whats the point of downloading megabytes of javascript, calling 80 different endpoints and then generating what could've been statically saved from the beginning and sent in a single request?

But your server has to render it for the thousands of visitors to you site. I still don't get the rationale.

Smart rendering would involve using a mostly static template that's updated with the relatively few dynamic elements as the page is being readied to be sent over the wire. If 90% of your dynamic content is the same, why put that through your app processes at all?

Static stuff is static at either end, and doesn't add to rendering time.