I think completing hardcore games serves as a right of passage. It’s how we separate the men (and women!) from the boys, and acts as our hazing ritual. Dedication to git gud means dedication to the art and understanding and appreciation for its nuances. Even disabled gamers are often able to git gud to the extent necessary to enjoy a game. It acts as a meritocratic filter that in part separates out the ever-present threat of hipsters ready to cultural appropriate the best parts of gaming culture.
Even casuals git gud in their own right. To reject the notion of self-improvement in regards to video games is anathema to rejecting video games themselves.