It's usually done as a strategy to try to fit in, to be "one of the good ones," or sometimes just self loathing given a signal boost by chuds in the same community.
It's saddening how many people, especially trans people, call themselves d-word-popularized-by-nazis, for example. Or marginalized ethnic group members that use the very slurs that are used to justify putting people like them into camps.
It's fucked up, but I am often at a loss for how to reach those people, or if such a thing is even possible. :doomer:
EDIT: It seems this is important enough to :freeze-gamer: that alt accounts must be mustered to rage at me about it. :jokah-messy:
This was always my understanding of the term, as well, and it's the only context in which I continue to use the word. I casually understand "d-generate gameplay" as something that circumvents the game's mechanics, producing strong, simplified play, that's also significantly less fun / more annoying.