In this context there should be no confusion or debate about what a standard is.  We are talking here about the RDF standard -- a W3C Recommendation that defines RDF.  There is no fuzziness about it.  The RDF specification goes to great lengths to ensure that the dividing line between what is or is not a part of that standard is crystal clear.  It is essential that this line not be muddied in any way, and that readers are clearly warned about features that would put them outside of the standard.

Including even an informative definition of "generalized RDF" in the RDF spec substantially *increases* the risk that someone may mistakenly believe that "generalized RDF" is some form of standard RDF, when it is not.  It is an *extension* of RDF that does *not* conform to the RDF standard.  Hence it is all the more important to visibly warn readers about the use of generalized RDF.

Actually, the more I think about it the more I am convinced that the inclusion of the definition of "generalized RDF" in the RDF spec *at* *all* is a big mistake, because exactly this kind of confusion already seems to be happening.  I will lobby the RDF WG to remove that definition from the RDF spec.  If the definition is removed from the RDF spec, then I guess it could still be included in the JSON-LD Syntax or API spec, but I still think it is essential to very visibly warn users of any feature that would result in non-standard RDF.