A thought if you want to sell to companies, "with per-user keys that get shredded when a user decides to delete their account."
You'll need soft delete, work messages belong to the employer and not the user.
You'll need soft delete, work messages belong to the employer and not the user.
For some you need legal holds on employee messages and in other cases you will want to un-delete messages for investigations etc.
For just random online communities, which is the niche discord is in, I agree it does sound nice.