They need reinforcements for manual tasks and handling small-time fodder.
You need powerful individuals to fight powerful individuals.
Crazy how illiterates read a manga for 1073 chapters and still pretend to be unaware of the power that numbers provide. LMAO
Having more men in a confrontation gives a numerical advantage to the larger group, they can surround and pressure the lone opponent, which makes it difficult for them to defend and counter-attack. Additionally, a larger group can also split into teams to perform specific tasks, such as surrounding the opponent, distracting them, or attacking from different angles. Another advantage is that the larger group has more resources to spend and more men to replace the injured or killed, making the fight longer and more exhausting for the lone opponent.
At the moment when the numbers distract Weevil, GB attacks him and so on.