In the real game those werent mandatory for most of OW1. 99% of the playerbase never felt they were forced to play determined tank duos until Blizz nerfed tanks into being killeable by flankers and snipers.
By the end of OW1? Sure. But that is because by then most tanks were husks of what they were and tank synergy was the only thing that heroes like Orisa could do to have some value after getting ran into the ground for the sake of Ashemaker 76 mains.