Prowler is not very good against Goliath because the Goliath can deflect, and its deflect ability unstealths the Prowler. Only a Goliath who has bad reflexes and goes in a straight line gets hosed. And one rocket doesn't kill the Goliath. And as soon as they know Prowler is on them, they're on their toes.
Even in a FFA game a Goliath is easy to take, but only once they unloaded their energy bar or took a few hits. Other players can help with that, consciously or not. And if the Goliath has a large bounty on their head, it is in their interest to help. FFA isn't literally FFA all the time. Sometimes interests align. The bounty system aids that, and its fun. K/D ratio is the real, publicly hidden score.
As a player you should avoid being near the spawn points. You learn where they are after a while. Planes always spawn facing north.