Wikipedia is an interesting case when it comes to SEO. On the one hand, they’re an incredibly massive, high profile site full of authority. They have authority in a web sense, and authority in a factual sense. They’ve become a dominant informational source in dozens of languages around the world, despite being able to be edited by anyone with an account.
While you might think that makes it an excellent source for backlinks to rank a site, you might be wrong. The last bit there, the part where anyone at all can edit a Wikipedia article, makes it a problem for someone like Google. If they want to count links on Wikipedia as authoritative, they have to take into account the fact that anyone – including the owner of the site being linked to – can add the link to the page.
It does no good to count a link as a source of authority and a recommendation when the link is from the owner of the site being linked. That’s the same reason private blog networks are a bad idea, and why linking between several sites you own is considered bad practice.
It’s also a problem for Wikipedia. If you owned a site like Wiki, would you want anyone and their mother to be able to use you for lin…