That depends. Some people are really good with those snipers and take out a lot of the harder mobs that spawn with ease from above while just one can clear out the easy mobs below. Sure 3 people with loaded rockets will make it faster but i dont really think its making it any slower have people sit back and sniper. They are still killing and killing pretty fast if they are atleast DECENT with a sniper rifle. Also they just got a new toy. Let them play it.