We already saw these fellows are busy fighting each other, so it's pretty much given Strawhats don't need to beat all of them. If your post was a response to mine, though, I never meant they would beat all of them. But seeing how there are eight parties there (in addition), it's far from inconceivable they would need to fight more than one. If that happens at the same time, it would mean more than one enemy captain to handle.