It is now possible (but not easy) for anyone who is determined enough to create a xanadoc, and send it to others, who may open and use it.  (Note that the World Wide Web was available for several years before the Mosaic editor made it easy for the public.)

A brief and extremely biased timeline of standardization

In the early 1990s, the creators of Netscape apparently built a function that enabled each web page to be annotated by those visiting it, as a way for viewers to discuss the page’s content. But according to a [1] produced in 2013 by a nonprofit called [Hypothesis][2], the feature was turned off.

the main reason we built a new multiprocess architecture is that Chromium's multiprocess support was never contributed to the WebKit project. It has always lived in the separate Chromium tree, making it pretty hard to use for non-Chrome purposes.Before we wrote a single line of what would become WebKit2 we directly asked Google folks if they would be willing to contribute their multiprocess support back to WebKit, so that we could build on it. They said no.