My anecdote may not be representative, but in my experience, Minecraft was able to spread and become a massive fad among elementary school age kids because they

My anecdote may not be representative, but in my experience, Minecraft was able to spread and become a massive fad among elementary school age kids because they could download it to their Xbox. All the kids I know who play Minecraft do it primarily on the Xbox until they get really into it, at which point they convince their parents to let them download it for the PC.