Officers are there to lead (it's sort of by definition), and to think that it's all just a matter of distributing loot is a very bold understatement of what they do. It's not an easy job (and not everyone is going to be good at it) and it's what keeps the group working coherently -- imagine a sports team without a coach, or an army without a general, that sort of stuff. There's a lot of things they do and much of it isn't actually visible to most raiders.
The other downside of not having an officer is that people will run into arguments and disagreements because everyone tries to have their say in a group without any arbiter to decide what's what. People try to fill in the vacant leadership role and this leads to confusion and chaos.