Why are sleepovers considered so important ?

My children are older teens now. As little ‘uns, we only allowed sleepovers with family - grandparents every weekend, and less often with cousins, I’d guess about twice a year. We agreed to sleepovers with friends from the age of 10/11, but tbh they both hated it then. Guess they didn’t like being in a strange house overnight. But from the age of about 14, they both actively asked to go to sleepovers and also host it, and at this point they genuinely enjoyed the experience FWIW, we didn’t encourage sleepovers at a younger age, not because we thought anything bad would happen, but because I hated the idea of being responsible for another child overnight. I didn’t think it fair to send my children to another house when I was reluctant to reciprocate. So no to sleepovers, except with family, just seemed reasonable. From 10, children are fairly self-sufficient, and don’t require me to parent them, so I was happy to host. Currently, as older teens, they even cook their own breakfast and order their own dinner, so I am very very flexible with sleepovers.