PVP question

Maybe a silly question, why PVP don't allow both players to pick the same faction? I'm confortablly playing with 2 factions, so when these two are banned and picked, I have to play with the third one which I seldom pick (it's relatively weak for me). I have over 150 game experience but I don't think I have mastered my main factions yet. And in pace with my MMR going up, I have to compete with better players so even my main factions can hardly match.

If both side can choose the same faction, better chance for me to pick my main factions and I don't see any reason that will cause disadvantage to the opponent.

Also for heros with creature specializion, the description "..., and enemy creature lose an equal amount of attack and defense" is acturally working in the case.

I am not saying to alter this mechanizm entirely for all the existing models, but rather add one more model that allow it.