You need to keep your finger pressing the off button on the remote until the whole thing turns off.
When you press the power button and it goes to art mode (effectively a screensaver) instead of turning off, most people's next step would be to try holding the power button. Barring that, the manual clearly describes these two different operations if the power button.
You would do well to work in tech support for a few months because this claim is absolutely a complete fantasy.
And now I just discovered my Apple TV actually has a control panel. You don't need to go two layers deep in Settings to put it to sleep. It never occurred to me to a long press on the home button would do anything. (Despite knowing long pressing on the menu taking you to the main menu.)
I would really think twice before I bought another Samsung consumer product.