Oh, thank God. Yes, this is blatant disregard of Postell’s Law, but one of the beauties of XML is that you can assume away parsing. Once a big player gets permissive, feeds get sloppy, everyone has to special case their parsing, and you get HTML.
Plus, the only people who have to get it right are the blogging tools. And Zeldman. And we’re all of us smart people.
(Another great tool that assumes away parsing: LISP. And that enables macros, which are useful.)
[via Niall Kennedy]
More reading: Dave Winer has a good essay on the subject, even if it hints at a Brent-Simmons-wants-to-make-feed-reading-hard conspiracy to dominate the market.