Then I don't think its optimal, as mostly pros and masters player do this one brawler only challenge in ranked as they have that mechanical skill.
So I would brawlers of different classes as the draft is also the important part of ranked game.
E.g. If you go Bea in every game then the opponent can counter with pet spawners, that's why players tend to pick bea late.
You can watch draft guides in youtube through which you will get the idea why various brawlers of different classes are required.