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?
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