Hindsight bias is when you pretend to have always known the outcome after having seen the outcome. Saying "it was obvious you were maf" should not be taken as a serious comment, and anybody who says it without actually explaining why they "always knew" should not be taken as a serious person. People who are told this should not believe that they are bad at being maf and should not quit the game.
https://www.youtube.com/watch?v=KNZSXnrbs_k