> - SLA guarantee (yes this a hidden cost, e.g. if your DC power is out, you owe your customers fees depending on your SLA).
But Amazon and GCP can go down too and their SLA does not necessarily fully insure against your SLA.
But Amazon and GCP can go down too and their SLA does not necessarily fully insure against your SLA.
The crux of this is how do you compare in managing site reliability. Perhaps you have a world class team you could do that better than yes my point there is moot. But 99% of the time, it's not.
And, frankly, your parent was being generous. Even if you only look at elastic workloads, the workload has to be a) extremely elastic and b) not fall into some pretty common patterns for cloud to make any kind of sense.
Also, many have been in operation since before AWS was a thing, and some are larger. So I can't imagine what AWS knows about running a datacenter that others don't.
Now maybe in theory if you can build something to be fully one with the cloud, considering all edge cases, and limiting yourself to only cloud-zen tools (or building your own, or doing vendor lock in). In theory, with enough money, I guess the cloud lets you maybe achieve higher reliability.
The fundamentals of EC2 (lack of dual NICs, dual power supplies and BBU RAID + virtualization and general complexity) means that a single instance is way less reliable (let alone, much worse value) than a single dedicated box. The complexity you need to throw on top of that building block (in the shape of lock-in, compromise, money, latency, application complexity or a combination of these) is pretty significant.
Building out your application across multiple regions in AWS is not much different than using multiple DCs from a managed host. The clouds provide live migration, spot instances, and fast global VPC networks that can make it much easier, but you also pay the premium for it.