I don't understand this parent. "I let my son play minecraft in the morning before school" - so your son is slacking off in school, but you're still giving him everything he wants? He's your son. He needs to be shown that sometimes, you have to suck it up and work, even when you don't want to. That's a tough lesson to teach an 8 year old, but it's something that parents should enforce early. Eventually, their kid will see that hard work and self control will pay off. Here's a novel idea - don't let your kid play minecraft until he starts doing better in school.
That being said, I do think physical activity should be more common. If it's rainy or cold out, kids should be able to go to their school's gym for an extra PE class - or maybe be able to play minecraft on the school computers. Boys and girls needs to be able to do something like this throughout the day. Article like this will hopefully make schools rethink some things - but until change actually happens, this mom needs to take control instead of just throwing her hands up and telling her son "it's not your fault. now go play minecraft."