"precursor of html"
please elaborate.
HTML is based on XML, a language with two primitives, strings and children. Why would you ever use that as an interface if you want something to ever be performant?
What we need is a retain-mode scene graph, where some of the nodes on the scene graph can be HTML documents (with URIs).
Developers don't want a one-to-one relationship between the window object and documents. They instead want a one-to-many relationship. The <article> tag is proof of this.
Take Twitter for example. What is each tweet, but a 140-character document? The application for displaying an infinite list of tweets is not a document, but a multi-document viewer. The Facebook feed is the same thing.
If anything, this would prevent the shenanigans of blocking viewport resizing, because the user could choose an HTML document node on the scene graph and decide to make it full screen (the same way twitter allows you to click on a time stamp to get a permalink)
This retain-mode scene graph would need to support URIs so that you could always link to a subgraph of the scene graph and only view that part.