Seriously, why can't the same page just be responsive? Why do we need two different domains even, instead of the server serving a desktop or mobile page? Why does the mobile page not redirect back to desktop?
The Wikipedia page is just responsive. The Wikipedia Mobile page has a dedicated URL, and it assumes that, if you went to the trouble of requesting it specifically, that's because you specifically wanted it.
But it doesn't, if you go to the desktop site it redirects you to the mobile site. The desktop site isn't responsive, you get the desktop view on the phone, sidebar and all.
So many odd choices.