They are the one that controls finances in the household and what their kids own.
That’s why the kid was distressed and the relationship with the father went south, because he said “no” and tried to help his child. That’s the point when kids start to sell their belongings to school mates, steal from parents purses or take their credit cards or spent all money they make with a job on the game and even when they have no money to spent, their minds are in the game all the time and family life is 99% fighting about screen time.
This is not solely about parents not restricting money, this is game developers and publishers hiring psychologists to find ways to make their games as addictive as possible vs. normal people and their children, a multi billion industry vs. ordinary customers. To blame this solely on parents is just wrong.
They probably allowed the kid a decent amount of screen time and some money to spent, like normal parents do. That their kid got pulled into an addiction by an industry that does everything possible to make that happen did happen over time, hard to notice until it is already a problem.
Most people blaming only the parents do not have children and have watched their child cry for days because it can’t have the skin “all the other kids have” and therefore gets bullied in school. All these games on purpose work with group pressure on top of addictive game and loot mechanics. They prey especially on neurodiverse children and adults, FOMO and more.