Creating a Geni profile without reference to sources lessens the reliability of that profile, unless information is readily found e.g. in available church records. Therefore it should be strongly recommended to mention used sources in most cases.
There has been some discussion on the (un)reliability of Wikipedia. But perhaps we should not generalize too much about our views on Wikipedia.
As an example of using Wikipedia as a linked source for a profile: Duke Eric II of Pomerania (ca 1425 - 1474, @Erich II af Pommern-Stolp-Stettin II) is documented in several language versions of Wikipedia, and in these articles other more primary sources are mentioned.
http://en.wikipedia.org/wiki/Eric_II,_Duke_of_Pomerania
http://de.wikipedia.org/wiki/Erich_II._(Pommern)
The more primary sources mentioned in these articles are in German:
ttp://daten.digitale-sammlungen.de/~db/bsb00008364/images/index.html?id=00008364&fip=91.154.248.201&no=5&seite=209
http://www.genealogie-mittelalter.de/pommern_herzoege_von/erich_2_h...
If such sourcing can be found in a Wikipedia article, wouldn't it be a quite sufficient criterion to rely on this particular article? In addition, there would be no need to copy text from the Wikipedia article, only add the link to the "About Me" section of the profile.
