Think about it like the mission dealer event box. Think of all the players on your server getting ~70 boxes to open over the week. 20-50 people on your server. So, that is 1400-3500 boxes opened every week that event happens. Each box costs 20 coupons if I remember right. So, the value of opening all those boxes is 28k-70k coupons each week. Now ask yourself, how often do you see an announcement of someone getting Hashirama x80. The chances of getting Obito are probably lower than that.