I disagree with the point that as a pure carnage simulator, "Doom is the closest thing you will be to a pure instrument of destruction whose sole function is to search and destroy", and that it stands the test of time as the greatest in the genre.

The Serious Sams, Bulletstorm, Painkiller (and others) have taken the Doom experience of finding a horde of somethings and killing them into the modern era, each with their own take.

Serious Sam expanded the levels and monster counts to a grotesque scale, allowing for perverse satisfaction in watching and killing off a distant and vast sea of fodder running towards you.

Bulletstorm lightened the mood, and as a precursor to the Gears of War series, was the first in my mind to make the action movie tropes of kicking and punching things, coupled with cheesy banter, genuinely pleasing.

Painkiller took the heavy metal influences, and merged them with some of the great settings from the previous century of horror novels and coupled it with immersive and creative level and weapon design.

I definitely believe that Doom was the original seminal piece in the genre, a Tolkien-esque work. But mankind has improved on the experience in the years since. Try those out too.