This is exactly how I view Doom as well.

If you want lore, put it in the environment. Let people hunt and find it (makes it more rewarding for those people too). But the core gameplay loop of doom needs to not have hours of exposition dump. The whole point of Doom guy is literally rip and tear. Not to give a shit about why he's ripping and tearing. He's a Marine. Simple motivations.

Source:https://doom.fandom.com/wiki/Doom_Slayer

The Doom Marine was originally a human from Earth who served in the Marines and was dishonorably discharged due to assaulting his commanding officer after refusing to fire upon a crowd of unarmed civilians and was later transferred to the UAC Phobos base as security. The Marine soon found himself trying to prevent the demons of Hell from invading Earth. After having fought demonic hordes through Phobos, Deimos and Hell, he returned home to find Earth now overrun by demons. Among the billions of people killed were his family, including his pet rabbit Daisy, giving him further reason to pursue hunting the demons. He continued fighting the horde on Earth, before taking the fight to Hell once more.

There isn't a "reason" outside of pure rage that makes Doom guy. Doom guy would not give 2 fucking shits about "why", just murder and rage.

To tie this back to another topic, Mick Gordon fucking captured it perfectly in the music. No sense for the "norms" of music. Just pure rage in music form. It's cathartic. It was a perfect fit. And they fucked it up.