I don not think you could hold them responsible. Technology is the main culprit I think. When I was young we had only a ZX spectrum and frankly going out fishing or out on the BMX was infinitely more fun.
Games and social media are so good now it is easy to have fun without even moving your body for hours, except perhaps your hands. It's no surprise kids get their thrills from the PC, xbox etc instead of putting in any physical effort, it's the path of least resistance and we are genetically hard wired to conserve energy as historically it has been hard to find. That however takes my off in to a whole other contributory reason, high carb foods and there over availability.