Citing draft papers found on academia.edu I have noticed an article published in a peer-reviewed journal in which the author cites a draft paper posted by another person to academia.edu. The former gives the whole bibliographic information of the aforesaid draft (including the URL) at the exact place where it is cited, but does not mention that draft at all in the bibliography, even though she does give all other sources she has cited in the bibliography. 

Does it mean that a draft paper can be cited but should not be included in the bibliography? If it does mean that, is this because it is not yet peer-reviewed? I am rather curious here. 

(For those who need to know, the field is religious studies.)
In my experience, absolutely anything can be cited, but not everything should be cited. Papers uploaded to Academia can often be what's called post-print, i.e. they are the version that has been peer-reviewed, accepted by a journal but not copy-edited by the journal [this is the point where the article still belongs to the author, after copy-editing it is the property of the publisher]. In this case it would still technically be a draft, but quite a long way down the line. 

Of course the paper can be cited, as long as there is enough evidence that the research is of good quality [if it's been accepted by a journal then it generally would be]. Things that should be cited are works like academic books, journal articles; whereas things like Wikipedia should not. Then there are grey areas such as drafts and online articles: basically if you know the researcher and field, and you trust the quality of the research, I see no reason not to cite it and include it in the bibliography.