A WD document is the first form of a standard that is publicly available.
Commentary by virtually anyone is accepted, though no promises are made with regard to action on any particular element commented upon.
Recommendations can sometimes be implemented incorrectly, partially, or not at all, but many standards define two or more levels of conformance that developers must follow if they wish to label their product as W3C-compliant.
A recommendation may be updated or extended by separately-published, non-technical errata or editor drafts until sufficient substantial edits accumulate for producing a new edition or level of the recommendation.
HTML validators are invaluable tools for people that write code.