> imagine if we were strict on HTML validation You don't have to imagine it, this actually happened. I don't remember the details, but back in the HTML 4 era,

> imagine if we were strict on HTML validation You don't have to imagine it, this actually happened. I don't remember the details, but back in the HTML 4 era, there was XHTML, and if you gave it an XML media type, many browsers would parse it as XML and reject the entire document if there was any error (and display nothing at all but an error message). There were a number of articles and blog posts about this back in the day.