I watched the first 3 episodes of Mob Psycho and became an enjoyer. I think every good story has a MC with a character flaw/quirk that directly conflicts/interacts with their mission. For example, all powerful psychic who only wants to get jacked and talk to his crush. Or think about the Hobbit where being a homebody almost costs Bilbo the chance to go on an adventure to save the world. To that end, I think the only exception to the rule is a silent protagonist. Zelda from the Wind Waker doesn't talk, but you have this wonderful diversity of islands and dungeons to explore with bird people, plant people, and island boys. The story is simple, but that's not the focus of the work.