Some people attack this statement saying that "running around in an empty field" also happens in Minecraft and other survival games but I think the great difference is that minecraft is a sandbox game you can enjoy with your time and your pace, taking your time to build something, manage your crops, feeding your animals etc. There's a little bit of challenge, but its an "emptiness full of stuff you can do", something you cant in battle royale games since a game ends after a few dozens of mins