I think that only applies if the incoming load is gradual. Any sane elastic configuration has some timeouts and a measurement period meant to prevent unwanted s

I think that only applies if the incoming load is gradual. Any sane elastic configuration has some timeouts and a measurement period meant to prevent unwanted scale-up just because of transient load, and during that time you can get hit hard enough to degrade/take down your service before your additional capacity has come online. It makes sense to get out in front of known massive load events before they hit your service. If I'm launching a new service that I expect to hit the front page of HN, I'm spinning up capacity first and asking questions later. A couple hours of running large instances or extra containers costs much less than potential lost sales from users getting timeouts.