What is the purpose of the pain scale?

As a child I broke a leg and when asked at the hospital what level of pain I was in, I told them 10. It was excruciating and the worst pain I had ever been in. Then as a teen, I developed a severe case of inflamed bronchioles, and also said that was a 10 but IMO it was far worse pain. As a man I hear that kidney stones are one of the most painful things that can happen to me so that must be the 10 right? In both cases I don’t believe me saying my pain was a 10 changed anything at all, they treated me but I’d like to think they would’ve anyway.

Is it diagnostic or data collection, and in either case, is it effective?