So many people referring to using the button to turn the computer off, but more than 95% of the time, you use the OS to turn a computer off. It’s only when there’s a malfunction you would need to turn it off with a hardware button.
This button is primarily for turning the computer on.
Not if you hold the power button. Yeah if you single press a power button, the os can divert that, but long press, the SMC will cut power. Similarly how, pressing and holding the power and the volume down button on a phone, cuts power, even if the OS is hard frozen. Sometimes you just need an emergency exit.