I think that might depend on the age difference between the oldest child and the rest. You would probably leave either a 13 yo or an 11 yo at home alone at least in the daytime. Would you leave a 7 yo on their own? If not, the elder child is babysitting imo.
We didn't have adult babysitters too often, my parents thought we were well capable on our own. We weren't unfortunately due to bullying from eldest sib especially towards me, especially with fists etc. I'd err on the safe side with leaving children alone, they're not always as well-behaved as parents think or as brave. We were sometimes frightened when it was dark outside.