From D&D Wiki
D&D Wiki has an upvote feature at the bottom of each article. Users can click on upvote to show their like, interest, or satisfaction with an article. If an user ever becomes unhappy with the page, they can unvote.
Voting for a page doesn't make it better than other pages, nor does it imply any sort of quality for the page. In addition, a high number of votes does will not make an article automatically pass Featured/Quality Article Nomination.
The sole purpose is for users to interact and show a page their support when they don't have the time or cannot find the words to put on a talk page.