There is no practical reason to
generally underexpose by 2-3 stops for every landscape image.
Without more reasoning, it seems he matrix meters and then to ensure highlights do not clip, he underexposes. But this does not account for any other tones in the image, nor DR range of the camera versus the DR range of the scene.
My philosophy is to bracket when I'm in doubt. Not only is it more likely you will get a usable file, but sometimes compositing or HDR is worth doing even when you are not going for some oversaturated look.
Because of the extended DR of my D810 an how well the shadows lift, I have played with the highlight weighted metering mode as a way to "auto" meter while protecting the highlights, but I'm not totally happy with it in some situations, so I still bracket.
Any suggestions on why this might be a good idea? (Seems counter to the advice I've seen on LuLa and elsewhere.)