Google's pages don't validate. Nobody's claiming there isn't a reason for it. Naturally, one would expect Google to adhere to the standards. As you point out yo

Google's pages don't validate. Nobody's claiming there isn't a reason for it. Naturally, one would expect Google to adhere to the standards. As you point out yourself, they're smart enough to understand them. This is old news. Why is it relevant today? Because Google just released mod_pagespeed (http://news.ycombinator.com/item?id=1865249 http://news.ycombinator.com/item?id=1865249), an Apache module that speeds up pages by rewriting them, using filters based on optimizations developed by Google over the years. If you're a web developer that works under the requirement that all pages are valid HTML, it's important to consider the source before jumping on the mod_pagespeed bandwagon.