To downvoters: I want to let you know that Surveillance Capitalism really like to keep track of Serial Numbers, especially IMEIs of phones. If you happen to buy a used phone that a violent criminal used, you could end up with a no-knock warrant being served on you because they would be triangulating your phone with the IMEI, and the authorities think the criminal still uses the phone, not realizing they already sold it and got a new burner.

Very far-fetched, I know, but that's the worst case scenario. But there are also more common problematic situations you get get caught up in:

For Example: You could also get your phone locked because it was part of payment plan, and the previous owner stops paying (maybe because they lose their job or something), and sold the phone off to get some cash.

If you don't know, Samsung and Motorola (and perhaps other manufacturers as well) has the ability to disable your phone and hold the data hostage, yes, actually prevent you from accessing your data until you pay. (Carriers probably can't disable your phone, only block the IMEI, but if the financing goes through the manufacturer themselves, they could stop you from using your phone, even local access to files)

By the time you find out, you could be too late to return the phone or chargeback.

There's just too much that can go wrong with electronics, especially phones.