> where the server-generated HTML fragments were generic enough that the server and client HTML documents didn't need to know anything about each other's HTML.

> where the server-generated HTML fragments were generic enough that the server and client HTML documents didn't need to know anything about each other's HTML. > all these systems that did HTML injection over AJAX were tightly coupled That's because the presentation layer originated on the server. What the server didn't care about was the transformation that alters the display of the HTML on the client. So you can add add an extension to your browser that translate the text to another language and it wouldn't matter to the server. Or inject your own styles. Even when you do an AJAX request, you can add JS code that discards the response.