That's what the W3C has historically done, with HTML 2.0, 3.2, and 4.0. "Document, clean up, and nudge" is maybe a better description. The WHATWG today seems to take more of a "document, don't clean up, and add our wishlist" approach. (The "don't clean up" mentality is embodied in their "don't break the web" ethos; the "add our wishlist" mentality is a consequence of the "living standard" ethos… the "standard" never becomes reality because it is constantly changing.)
I'm not sure where you got this impression, but it's wrong. https://whatwg.org/working-mode stipulates the requirements on additions. That's quite a bit different from a set of wishes.
And there's a lot of cleanup of legacy APIs happening too. E.g., removal of the isindex tag and deprecation of AppCache.
