Basic replication is maybe close to what you could call solved, but I'd say that there's still complications like georeplicating multi master write machines are still quite complicated, and need a dedicated person to manage. Hiring being what it is, it might just be easier to let Amazon hire that person for you and pay Amazon directly.

I see cloud services as a proxy to hire talented devops/dba people, and efficiently multiplex their time across several companies, rather than each company hiring mediocre devops/dba engineers. That said, I agree that for quite a few smaller companies, in house infrastructure will do the job almost as well as managed services, at much cheaper numbers. Either way, this is not an engineering decision, it's a managerial one, and the tradeoffs are around developer time, hiring and cost.