That seems like an uncharitable take. It is entirely possible to re-sell a modern phone, and this happens quite often. Before selling the previous owner must sign out of the device's cloud account and perform a factory reset.

Differentiating between the intentional re-selling of the device, and the selling of a stolen device does seem like a tricky problem, and personally I think this solution seems reasonable. If the device manufacturers are at fault of something it would be poor UX for not making this more clear, otherwise I believe these companies are acting honestly here.