What does iCloud locked mean, for Apple?
The disadvantage is that without the AppleID and passcode used to originally setup the iPhone, you will not be able to activate it. You will not be able to complete the setup process. You will have an unusable iPhone.
Find My iPhone includes Activation Lock—a feature that’s designed to prevent anyone else from using your iPhone, iPad, iPod touch, or Apple Watch if it’s ever lost or stolen. Activation Lock is enabled automatically when you turn on Find My iPhone.
Before you give away your device or sale
Make sure that you turn off Find My iPhone on your device before you give it away or send it in for repair. Otherwise, your device is locked and anyone that you give the device to can’t use it normally and Apple technicians can’t perform service repairs. Just sign out of iCloud and then erase all content and settings. This completely erases your device, removes it from your Apple ID, and turns off Find My iPhone.