If a person is watching teardown videos only to see what circuitry is inside the boxes they are missing out on part of the learning opportunity offered by the videos. A teardown shows you see the circuitry inside the box and what parts are used but more than that, and equally as important, is how the circuitry was packaged. You can learn whether one circuit board was used or if there are multiple boards. You can see how the boards, and other items inside the box are mounted and interconnected. You can see how the displays, buttons, knobs, and switches are mounted, and how they are connected back to the main circuit boards.
There is more to electronics than just making a circuit that works if you are trying to create a product.