I have been doing web development for a while now and up until a few years ago I would validate the HTML and CSS of the sites that I built. Is there any value in validating HTML?<p>As an aside, HN has quite a few validation errors: http://validator.w3.org/check?uri=https%3A%2F%2Fnews.ycombinator.com&charset=%28detect+automatically%29&doctype=Inline&group=0&user-agent=W3C_Validator%2F1.3+http%3A%2F%2Fvalidator.w3.org%2Fservices
Yes!<p>Having HTML and CSS that doesn't validate is fine if you understand why it isn't validating and you understand the consequences.<p>In my opinion the robustness principle (be generous in what you accept) is harmful for the web; there's a lot of broken markup lying around.
Given the value attributed to shipping and <i>minimum</i> viable products, I find it appropriate that HN has validation errors.<p>Perhaps we should design an image badge that says "This site has invalid HTML!" to go along with Reid Hoffman's motto, "If you are not embarrassed by the first version of your product, you've launched too late."
I do it personally because I like having the validator saying "0 validation errors!" Fixing the errors in entertaining work. But honestly, for production sites, it doesn't matter one bit if the site has validation errors or not.