Dave Mark, writing for The Loop, on the removal of Apple’s online iCloud Activation Lock tool:
[Here’s] a video that shows how to unlock an iPad by cloning the iPad drive and changing the serial number to a valid unlocked serial number, one checked/validated using the Apple activation lock tool (about 5:28 into the video).
My guess is it’ll get replaced with a more secure system, though I’m not sure how such a system could be made available to the general public the way the iCloud tool was without suffering from the same abuse.
In the meantime, if you’re in the process of buying an iPhone, iPad, or Apple Watch, make sure you verify they’ve removed Activation Lock in person before completing your transaction or stick to buying from a reputable service with a return policy in case of errors.