In T60425#604115, @MaxSem wrote:

This is intended behavior - if you've accidentally ended up on mobile site, there's always a link back to desktop. However, mobile site is not restricted to mobile devices and there are even some people who prefer to use it from their PCs.

When mobile users post wikipedia links, it's to the mobile version of the site. This happens on reddit frequently, because a substantial proportion of users are on mobile devices.

Viewing the mobile site on desktop is not desirable. The desktop site uses most of the screen, whereas the mobile site leaves plenty of empty space on both left and right sides of the screen and uses a larger font. There's not nearly as much text visible on the mobile site.