“Variations
“Marty Stu”, “Gary Stu”, or “Larry Stu” are alternative names given to this trope, when the same wish-fulfillment aspect is applied to male characters.[15][16] The Star Trek: The Next Generation character Wesley Crusher was described, in hostile terms, as a “Gary Stu” by the feminist popular culture magazine Bitch.[17] There is speculation amongst fans and academics, mainly pejorative, that Wesley was a self-insertion character for Gene Roddenberry, Roddenberry’s middle name being Wesley.[18]”
A Mary Sue character is by definition flawless and has no need to change. As a result, they’re boring characters in any story as there is no question of them overcoming anything. Who wants to watch boring characters?