Building a dashboard by clickety/clacking around is not a menial task, consistency across dashboards is a a core unit of observability to ensure x-functional teams can discuss issues across a common language/viewpoint, which is only enforceable through a declarative dashboard syntax.
The question was regarding alerts, not dashboards. We obviously deploy dashboards from json.
But I'm not aware of any way to deploy notification channels, probably can do that now via API. But either way we need to deploy notification channels with webhooks and tokens so that part is done manually. And then the alerts is also done manually.