Party voice chat is done in other pvp games like online shooters and its integral part of these games. Like in Battlefields you can que 'solo' but can talk with your random party members. Or not talk, the choice if you need that advantage is yours. Just because this game doesn't have this feature built-in doesn't make it any more cheating. It's not there for the same old 'possible harassment' reason or just not enough budget/PS3 limitations.
PvP Discord is available to everyone, even for Playstation players who can use it on mobile phone, so if they want voice communication is up to them. The advantage is overrated though, even if you get all 4 players in voice chat you'll still lose against a better team without it.