Must you have an @icloud.com email to set up Mac products

My fiancé claims he’s never had an @Icloud.com email but that he just uses his gmail account and set up his Apple ID that way? I see linked contacts under his name say Exchange,Gmail and yahoo. Also his photos are different with using ICloud and Yahoo shows up under his name on the contact when he claims his old Yahoo is inactive?

i was under the impression that anyone using Mac products has to have an iCloud.com email and Apple ID. Then later can add other emails as main domain.