It's also not just cost/availability, but flexibility and scalability. Most high-growth startups would have not been able to scale quickly enough pre-cloud. Facebook is literally the unicorn.
Scalability is a niche perk of the cloud, absolutely. I work somewhere that has a customer base that does not meaningfully scale, so it's not a concern for me. But then: Once an organization has established and has a relatively predictable scale rate, they should exit the public cloud if they can.
An established company with a stable capacity need shouldn't ever be moving to a cloud provider with a generous big tech profit margin. But that also poses a risk for the scalability of the cloud: If you don't have people overpaying for stable capacity usage, can the cloud provider afford tons of extra capacity for flexible needs?
I’m not a fan of the cloud. But if you’re too small to have your own data center and support team, the cloud is absolutely a good option.
Overall, our 10+ year old infrastructure has hugely outpaced reliability of any of the three main clouds (and brough in more business since we got customers when the main clouds killed most of the internet).
Why do you keep behaving like reliable infrastructure was impossible without paying rent to american bigcorp?
(This doesn't mean cloud doesn't make sense for many people, but, seriously, cut the crap.)