The assumption that forums are a dying medium is pretty preposterous.
Mechanically, I’d argue that places like here, reddit, facebook, and other social media are actually regressions in communication between the stripping of features older software had and pushing new schlock, sometimes in its place, that isn’t nearly as effective.
Discord is also not a substitute, as while it may lend itself to real-time communication, you’re unlikely to have people backscrolling through longer conversations. Things also not being available in web searches for quick reference is also a strike. Search features within Discord itself are something I’d call spotty at best, nevermind the continued inability to manage multiple accounts within a single instance of the program.
Memes and zingers do not make a community, no matter how much those with shorter attention spans might think otherwise. Any company that does not set up their own official site for communication, let alone make it priority, is failing to put their best foot forward. D3 has failed here for sure, but this also wouldn’t be the first time I’ve criticized their hands off approach to community.