There seem to be plenty of successful online businesses that share some information about their back end infrastructure, and when you look it turns out they jus

There seem to be plenty of successful online businesses that share some information about their back end infrastructure, and when you look it turns out they just have a handful of web servers running their app behind a load balancer, enough DB servers for the throughput and redundancy they need and some sort of failover arrangements in case something dies, and some sort of cache and/or CDN arrangements just for efficiency. Even if they're running in the cloud, it's probably just a load of manually allocated EC2 instances, maybe RDS to save the hassle of managing the database manually, and maybe S3. I wonder how many businesses exist in the entire world that truly need to scale their server counts up or down by a factor of several so quickly that it has to be done automatically and not as a result of, say, daily human reviews of what's happening. I feel like even large businesses that need to run thousands of servers at all are probably relatively rare, as indeed large businesses themselves are. The number that might realistically need to scale from say 1,000 web servers to 1,500 within a matter of hours must be even rarer. But I have nothing even resembling a useful data source to tell whether this intuition is correct.