But why would shopify ever treat a subdomain as an entirely separate store outside of the main domain? That makes no sense. If i register xyz.example.com as my

But why would shopify ever treat a subdomain as an entirely separate store outside of the main domain? That makes no sense. If i register xyz.example.com as my store, then that should just be in my ONE account which verifies example.com, then by adding a second store, i can only add it as a subdomain from that main account, not just an entirely separate account. Or, lets say its a separate account, then it should make me add records from that NEW account, even if there are already existing records. So i still dont understand how this is possible