rlange - 5:41 pm on May 3, 2012 (gmt 0)
Proper formatting and completeness isn't optional.
Well, in HTML5, for certain tags, it is: The HTML syntax - Optional tags [whatwg.org].
This isn't Google trying to redefine standards. Closing a <p> element is technically optional in HTML5 (but still looks so very wrong to me).