User blog comment:Thereselovesyou/VOTE: The Greatest Couple in Fandom Tournament/@comment-172.249.166.3-20170129234442/@comment-8043962-20170130095206

Ships can be both canon and fanon. The Shipping article on Wikipedia explains that a canon ship is a 'type of ship'.

The tournament is only for canon ships so that's the reason for why Mary and John are here, instead of Sherlock and John. But, the overall wiki is however for both canon and fanon ships

(I am also disappointed that Yuuri and Viktor aren't listed)