Business services generally need high availability goals, so often that doesn't cut it. And your single server doesn't autoscale to load.
AWS gives you availability zones, which are usually physically distinct datacenters in a region, and multiple regions. Well designed cloud apps failover between them. Very very rarely have we seen an outage across regions in AWS, if ever.
In practice I see a lot of breakage (=downtime), velocity loss, and terrible "bus factor" from complex Cloud setups where they're really not needed—one beefy server and some basic safety steps that are also needed with the Cloud, so aren't any extra work, would do. "Well designed" is not the norm and lots of the companies are heading to the cloud without an expert at the wheel, let alone more than one (see: terrible bus factor)
Businesses always ask for High Availability, but they never agree on what that actually means. IE, does HA mean "Disaster Recovery", in which case rebuilding the system after an incident could qualify? Does it require active-active runtimes? Multiple data centers? Geographic distribution?
And by the way, how much are they willing to spend on their desired level of availability?
I still need a better way to run these conversations, but I'm trying to find a way to bring it back to cost. How much does an hour of downtime really cost you?
Agree - different business functions have different availability goals. An system that computes live risk for a trading desk might have different availability goals from an HR services portal.
AWS gives you availability zones, which are usually physically distinct datacenters in a region, and multiple regions. Well designed cloud apps failover between them. Very very rarely have we seen an outage across regions in AWS, if ever.