[ncphil]

Not so sure older content (like the stuff I wrote in the late 90s to mid 00s) would be negatively impacted, so long as search providers pay careful attention to the <!DOCTYPE> tag (or lack thereof). I wouldn't characterize holding people to at least a bare minimum of standards (e.g., title in the head and nowhere else, which has been the rule since at least HTML 2.0 in 1994) as "punishment", any more than dinging them for unclosed parens and other typos. Language is how we communicate understanding, and markup is how we frame presentations on the web (mostly). People need to be prepared for the consequences of making it up as they go along rather than educating themselves on the standard (whether spelling, grammar or markup language).

[marginalia_nu]

That really doesn't seem to be what I'm seeing, having built a search engine specialized in this type of content and finding almost nothing but gems in the refuse.

If anything, it seems like the single best predictor of whether a website is a content mill is strict adherence to modern web standards and other "google rules".