I wish people who know little about HTML, XHTML and CSS wouldn't write such posts just for the hell of it. Jeff is a respected programmer, but front-end developer he is not.
I'm not going to go into details of why he's wrong, because a) this has been discussed to death by people who actually matter in this space, and b) there's a ton of comments on his post explaining what's wrong with his view.
There are ways to argue that validation is unnecessary; however, they do not include: 1) bringing up examples such as "target" attribute, and 2) saying "who cares if it works anyway."
He does seem to be pretty misinformed. For example, he chooses to validate against HTML4 strict, and then compains that attributes like target and width don't validate. However HTML4 includes two additional doctypes (beside strict): transitional and frameset, exactly to cater to people like him who like to use frame-related features and presentational HTML.
His argument about user-generated content is also spurious. If you dont parse and filter user-generated content (with a real HTML-parser, not just regexes), then you are vulnerable to script-injection attack.
I'm not going to go into details of why he's wrong, because a) this has been discussed to death by people who actually matter in this space, and b) there's a ton of comments on his post explaining what's wrong with his view.
There are ways to argue that validation is unnecessary; however, they do not include: 1) bringing up examples such as "target" attribute, and 2) saying "who cares if it works anyway."