I would guess it's more of a reference to older, more grind heavy MMOs such as FFXI. I loved FFXI but if you weren't putting in a bare minimum of 20 hours a week with 40 hours or more per week being preferable, then you were probably not progressing in any meaningful way at endgame. That kind of lifestyle is unsustainable for pretty much everyone in the long term as outside needs will always catch up.