Clerick, I have nothing against fighting many vs one. The point is that, beyond a certain number, being too many becomes just pure idiocy and a tactical suicide: it's simply stupid that 10 or 20 friendlies follow a bandit, exposing themselves or the field they're defending to attack from other bandits/directions.... 4, 5 at most, should be sufficient, the other ones should think about the bigger picture and keep their eyes open for other bandits.
Otherwise, you would frustrate your own purpose, because you would end up concentrating on one single threat (and, let me state this, not such a big threat, to be honest, because if it has a lot of friendlies around, it can't do much damage or dropping unnoticed on your six), totally ignoring any other threat in the area, possibly much more dangerous that the one you're following.
Just take a look at this movie, you'll understand what I mean in my first paragraph:
Grits vs the Knights' horde