Because the articles have to be concise to be readable? For example I just stumbled into the article "Tinnitus" (http://en.wikipedia.org/wiki/Tinnitus http://en

Because the articles have to be concise to be readable? For example I just stumbled into the article "Tinnitus" (http://en.wikipedia.org/wiki/Tinnitus http://en.wikipedia.org/wiki/Tinnitus) which contains a "list of notable individuals with tinnitus" (given that tinnitus is common, this is analogous to a list people who like the colour beige). Makes the (medical) article a bit longer, but crucially it fills the references sections with totally irrelevant links.