thats just not true.
how can you even deny that being in a 3vs3 environment with 3 different specs which means more combinations of spells, tactics and CCs is not automatically more balanced than a 1vs1 scenario where options are just limited. It common sense. Its a fact. Its not even a debate.
Is arena perfectly balanced? of course not but its still 10x more balanced than 1vs1 can ever be just because of THE NATURE of having more specs fight each other.