The quite liberal free file attachment limits (25MB each), ease of communication and ironically the fact Discord is closed off in nature means it's quite attractive for people to more easily share things that would require a separate file host normally (it's an almost universal experience that forums usually have meager attachment caps).
I'd be quite interested in an article that understands Discord's benefits and use cases and then approaches a critique and alternative solutions to address it in a more open web friendly way.