Two consecutive comments to the submitted article:
"Google actually ranks it's indexed pages. The more valid the (X)HTML of your pages, the higher it'll appear in a search."
"If you do write XHTML, you'd better get it right. I heard about CodeProject practically dropping off the map because of an XHTML error that caused Google to stop ranking them."
Is this indeed documented or well confirmed behavior of Google? That might be a pretty important reason to validate.
As the Google crawler is a just a basic HTML parser, it makes sense that certain errors could cause major problems for a site — messed up nesting, missing quotes, etc. Google likely has fairly sophisticated error recovery in place, but I'm sure it doesn't cover everything. As such, it's always to one's advantage to validate their site in order to minimize friction.
"Google actually ranks it's indexed pages. The more valid the (X)HTML of your pages, the higher it'll appear in a search."
"If you do write XHTML, you'd better get it right. I heard about CodeProject practically dropping off the map because of an XHTML error that caused Google to stop ranking them."
Is this indeed documented or well confirmed behavior of Google? That might be a pretty important reason to validate.