It was probably some sort of sandbox game. I cannot see trying to giblet 500 on easy or normal when you can get a ton of damage points toward perk experience on Suicidal or Hell on Earth.
Some people tend to get wound around the axle about more monsters vice the quality and toughness of monsters in general. I went up pretty quick in perks by simply choosing to start most games on hard, then suicidal to ramp the perks up quicker. It still took many hours, but on the higher difficulty levels not only did it season me quicker, I knew what to expect sooner, IMO.