Connecting all of reality together
You wrote "The problem is... well, let's pull up a solid midlist Marvel  
character - Speedball. 1603 word article. Only 500 words of that  
pertain to the real world instead of the fictional world of the  
comics. That's the problem. Fancruft is in many ways a poor choice of  
terms for this. Especially since it's not even necessarily the case  
that the information itself is the problem. The problem is that  
virtually the entire article was written so as to pertain to the  
Marvel Universe, with occasional citations of issue number." here.

Which made me think of the problems in articles about economic systems in which enthusiasts pro and con anarchism and communism and capitalism go on and on and on with pie in the sky theories and barely coming down from their clouds long enough to source ideas much less tie ideas to concrete real word implementations of ideas (see mixed economy for the real world).

Which made me think of Wikipedia:Requests for arbitration/Pseudoscience/Workshop‎ in which the "science is based on evidence" clan does battle with the "ideas are science too" clan in the field of cosmology as it related to plasma.

Which made me think of Logical positivism which holds that all knowledge should be based on logical inference from observable facts.

Which made me think of our troubles in wording Wikipedia:Attribution‎ The point of attribution is credibility; which is achieved with an internal consistancy combined with connecting it all to objective reality. Sounds like our pop culture articles need to be grounded to objective reality to a greater degree. 

Which reminds me of answering "Because the author thought it would sell books" when asked why a fictional character displayed a certain psychological trait by an English teacher in my youth. But I digress...