Not terribly surprising. ARMS is a launch window title on a platform that has very little to offer right now. So, owners of the Switch are starved for games. Happens with virtually every new device. Games that release on it within the first 6 months to a year have higher sales than they would if they came later because people are just looking for games to justify the purchase. Splatoon released on a platform that was already considered a failure. It didn't even sell 15 million after almost 4 and a half years. The install base for the Wii U was embarrassingly low by the time Splatoon released.That and Splatoon was literally sold out.