Earlier quoted context omitted.
Those permissions are specifically granted "in connection with operating and providing the Service". I'm not a lawyer, but are you suggesting that they could do other things like steal your images to use in advertising and claim that it's "in connection with operating and providing the Service"? In order to host your (automatically copyrighted) content on their server and display it to other people in your chats they…
"Steal"? You gave them a license to do so. Yes, they could use your images in their advertising, or publish a book of your images, or make a movie out of all your messages and videos, or anything else they wanted to do with, as they call it, "Your Content". That's what a perpetual, transferable, worldwide, royalty-free, sublicensable license to create derivative works is. And no, all those rights are not required to…
>you grant to us a perpetual, nonexclusive, transferable, royalty-free, sublicensable, and worldwide license to [snip] Your Content in connection with operating and providing the ServiceSo what you're saying is that when you grant someone the right to use your content for a specific purpose, you're actually granting them the right to do whatever the hell they want with it?
Again, not a lawyer, but "in connection with operating and providing the Service" reads like a legally important part of that sentence to me.
"Service" in this context is defined earlier in the document:
>the Discord application (the “App”) or the website located at https://discordapp.com (the "Site"), which are collectively referred to as the “Service,”
IMO you're reading this very creatively if you think that grants them a right to publish a book of your private messages. Rights to use your content are granted specifically "in connection with operating and providing the Service." A book of your messages is not in connection with operating/providing the Discord app or website.