Notice the specificity of what's promised gone: death, mourning, crying, pain, not softened, not managed, but actually absent, because the old order of things has passed away. This isn't a coping mechanism offered for the meantime. It's the announcement that the entire system producing the grief will itself be replaced. And right alongside that ending, John doesn't just describe absence. He describes a river, water of life, flowing from the throne itself, life continuing to flow out from the very source of comfort.