Can an activation-locked MacBook ever be unlocked by a new owner?

There is a reputable seller on eBay selling a 2017 MacBook Pro that is locked with an activation lock. I'm a Windows guy looking for a MacBook and so this is new to me. If I buy this MacBook Pro, can it be unlocked? Would a new hard drive do the trick? Is it possible that it could be unlocked but stolen so it won't work no matter what I do? Thanks!