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?
