A lot of people, especially in casual debates on forums, use Wikipedia as a reference and sometimes even source material. In academics this is frowned upon, not because of disputes of its accuracy, but because you're supposed to read the source material given by any encyclopedia and cite that in your academic papers.
Wikipedia is a handy summery of numerous credible sources. They have a strict neutral point of view policy, and lots of policing to make sure sabotage and errors are fixed quickly.
This has made Wikipedia as accurate as Britannica when studied side-by-side
So next time someone you're arguing with uses Wikipedia as a source, don't cop-out and say Wikipedia 'doesn't count,' and argue the source material instead.