User blog comment:Pinkgirl234/Wikia Chat and Discord: The Pros and Cons of Both/@comment-6031945-20161015154141

"Conversations in Discord are not logged"

They are. It's just that it's tedious to look them as of the moment and some of the messages may be deleted by the staff members (although, an experimental search feature exists and a bot designed logging text that used to work isn't functional as of the moment).

Missing stuff:

Wikia Chat Pros
 * Users may use custom CSS and JS (as long as custom JavaScript is enabled via Special:Preferences) on chat, allowing a more powerful customization.

Cons:
 * As of the moment, it is a hassle to make it "data-friendly", requiring additional steps (and possibly more data) just to make it at such (which may or may not be improved in the future).

Discord Pros:
 * Music Streaming via certain Voice Channels

Cons:
 * On the PC standalone app, Updates sometimes fail repeatedly, requiring users either use Discord on their web browsers or change a certain file via their PC's file manager.

Needs to tested and be confirmed via evidence:
 * Data Usage (by average, at least)