Found on eightypercent.net:

"I just noticed that when RSS Bandit finds an invalid RSS feed, it offers to fork off to Sam and Mark's RSS Validator. ... I'm not making any excuses here, but I think that everyone can agree that one of the reasons that IE was so successful at that time was because it could consume everything that was already out there on the net -- and that meant very careful duplication of all of netscapes bugs."

The success story is true, but: HTML isn't comparable to XML. If people generate (or write by hand) a file named e.g. rss.xml it SHOULD be at least wellformed. If this isn't true, it is not XML by definition.Name it HTML and you will get at least the text within the elements within a browser, but nothing more. We do not want to write the 99'th HTML scraper/parser and do not want to repeat the same mistake twice a time.