Used to be: You throw a physical switch on the computer, it interrupts the power circuit from the power supply, and the computer went off instantly.
Today: You have to do it in some software menu, but invoking this, you're not even powering it off. You're requesting your computer to "pretty please, with sugar on top, turn off my computer when you're not too busy." Then the OS goes and does god knows what, maybe it decides to flush some caches, maybe it decides to do an entire operating system update, who knows--you're not the driver, you're just along for the ride.
Even the physical power button on the computer doesn't break a circuit anymore. It... you guessed it... sends a software signal begging the almighty operating system to please shut down.
And when you point this stuff out, all the excuses start coming out: "Bbbbut the OS has to flush its caches! Bbbbut the filesystem needs to write things to disk that are in-flight! Bbbbut applications need to gracefully shut down and free their memory (which is about to have the power cut). Bbbbbut there may be a critical background task still running that needs to...." I don't fucking care! I didn't command my computer to do any of these things.
It's gotten to the point where if you want to shut your computer down instantly, you need to pull the power plug or remove the battery. I expect we software engineers will fix that one some time soon, too.