This is a British website, which is I belive the region where Sony consoles do their best (amongst English speaking countries that is). The majority of the mods and content providers are British I believe. Consequently, they will focus on those things that they hear about in their general life. That is why VGChartz has such a comparatively small number of MS fans. Many Australian and American websites are very pro-MS, and thus MS fans go there.
There are a fair few Nintendo fans, keeping in mind the demographics of the two different consoles. Teenage males are the overwhelming majority of users on pretty much all forums. The Wii has a higher female userbase (and there are no girls on the internets), as well as more children and adults, who also aren't as likely to frequent forums as teenagers are.
