It seems like a lot of work, but if you work for organized crime, you pay kids to do it for a few bucks on a large scale and make a lot of profit.
The black market for iDevices is insane. Working at Apple, we saw many resellers every day. Same guy would come in every day with 2 phones that don't turn on, are registered to someone on the other side of the country, and they don't care about the data on the device. Usually they tell some ridiculous story (in very broken english) about how it's their sister's phone and she can't be here, and it got hot and doesn't turn on, yada yada yada...They come in looking to get them swapped for new phones. Somewhere down the line I am convinced that organized crime is involved.
My theory:
Phones are stolen by petty thieves on the street and out of cars...The thieves sell the phones cheap to people involved in organized crime. The phones are activation locked of course, so they can't just be resold. So they tamper with them and either switch the serial number (shown in this video) or make them unable to power on (usually by damaging certain logic board components.) Bring them to Apple, get them swapped for good new phones, and then re-sell...or better yet, illegally smuggle them back into China without paying taxes and sell them for massive profit. basically iPhone laundering
bro, if a device is activation locked.. you cannot bring it to the genius bar to get replaced m8 lol