Question: Just like the title says. Myself and a few other users have used Wikipedia as a reference while others use IMDb/articles/etc. 

We should establish here and now if this is a valid way to reference points/answers or not. 

My personal beliefs is that Wikipedia is not as bad as everyone says with referencing items and should any doubt arise, a person can simply use what the statement's citation for where the quote/idea/source came from and by that regard, still make the point valid. 

Also something that should be decided here is what we can/can't use as a reference. Do we restrict to IMDb or is any credible movie reporting site valid. What qualifies as a credible site, etc. All this should be in our FAQ as well so that we can instruct new users who want to answer questions.

Answer: 
Wikipedia varies in the quality of its content, and each movie page will vary in the number of supporting references. However a reference to Wikipedia is better than no reference at all, and compliments the factual detail of IMDB. This is particularly true when wanting to give someone an outline of a plot, which is often better on Wikipedia.
Wikipedia may have weaknesses, but I support having it as a valid reference because, on top of having own content, it also lists other (likely more authoritative) references. One other pro is that it is far cleaner than the UI mess that is IMDb.