This is not necessarily true. My parents had a Mac with an iCloud account and managed to purchase an iPhone from Verizon without ever logging into their iCloud account. It's one of the reasons I moved away from Verizon. They prioritized the sale of the device over making sure that people understood what they were buying and how to use it. Luckily, the iPhone is user-friendly enough that they were able to use it fine but they were never even asked if they wanted to enable iCloud and eagerly said yes when I mentioned what that meant.