But the thing is in most of the companies you don't have full control over the whole stack. Even if you have "full control" over the database, you don't have control over networking, firewall, OS, "security" patching, VMs, Docker, Kubernetes, Load balancers, vendors managing parts of the infra, internet provider, hosting provider ... Not even datacenter team may have control over all of it, but at least that's their job and their area of expertise.
And receiving a call and telling: "here's datacenter emergency phone, please ping them" or forwarding mail to datacenter team with "can you give ETA to the business" is an order of magnitude easier than trying to concentrate and resolve the actual problem while being interrupted every 5 minutes and not having required level of access to actually do it, even if the knowledge exists.
Though in most of the companies, business will not call you, but some poor business analyst or project/product manager, which will learn quickly to keep you out of the loop and don't waste anyone's time if you are consistent with answering "have no idea, ask datacenter guys".