They didn't need to. You can have a maximum of two 4* and the rest should be 3* (as all 2* and 5* are banned). The most you can have is 26*.
@KILI879, They didn't need to. Your deck's levels are so restricted the max is 26 levels.
@uno2003 you need to be a hero(The Hero rank is given to players with at least 20% of the characters.