[sublinear]

Because you want to offload all the work of rendering onto the client. And in fact you'd often want the rendering to be sensitive to the browser context. Different types of devices may require a different UI or arrangement of content. All that logic would be client logic. Why would you treat a browser different from any other client?

The presentation aspect is simply not the concern of the server in the first place. Data is not presentation and servers should be able to support more than one client. Data should be not be encapsulated in several layers of presentation. Having to scrape data from a web page is ugly and dumb.

[_heimdall]

Web technology is heavily invested in the goal of rendering content on the server and shipping markup and styling. The client browser still has to take the markup and render it properly, but the whole point of web architecture to begin with was to render data into markup on the server so the browser can be a pretty thin, standards-based rendering engine.

There are absolutely situations where web apps need to render most or all of the data into UI in the client, but that should be the outlier rather than the norm. Why do you assume that there are no situations when rendering HTML from the server is a valid, or even ideal, approach?

Even with native applications, the UI is a combination of content that is rendered on and off the client. An iOS app will end up with screens that are designed and rendered by the developer, the navigation menu and other chrome elements are likely rendered in the build, while some screens in the app do fetch data and render it to the screen. Again its very much the outlier to have a native app where the app entirely fetches data and renders all the content in the client.