With both whatever-apple-is-doing and Android’s whatever-it-is-called-that-prevent-factory-reset when you don’t have access to the account on the device, I don’t see how people still buy “shady” phones and tablets.
Last time I borrowed a relative’s phone to run an experiment, I had to contact them to “unlock” the phone after a factory reset before being able to do anything because I didn’t remove the account before. Unless people go out of their way to make their phone “stealable”, that is.