As mentioned in the article, the ability seamless failover to replica significantly reduces MTTR when the primary/master node fails. Also, Performance Insights (https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/USER_...) is really helpful chasing down slow/resource intensive queries.

That said, building a large, scalable Database still requires understanding the workloads and testing them out on production sized datasets. No easy button yet!