Why would you send Cronulla fans to Parramatta though? There's limited parking at CommBank (same as Allianz), so the majority of the crowd would likely be required to travel further and longer by taking three modes of public transport (T4 to Central, T1 to Parramatta, bus or walk to the stadium) in each direction.
Compare that to Allianz which is closer in journey time and distance, and requires only two modes of public transport (T4 to Central or Martin Place, with L2/L3 to Moore Park or 333 to Paddington) in each direction. This also (let's be honest) gives spectators more pre or post game options for something to eat or drink.
All Sydney clubs should be aspiring to play finals football in the biggest stadiums in town (i.e. Accor and Allianz).