I feel like this is really an American culture thing where parties or dinner parties are mostly the responsibility of the host. In movies or TV there’s even a common theme of guests judging the host’s hosting abilities. In Brazil you throw a party to people you like and they all have a hand in helping you, sharing the load. Everyone will be responsible for some part of it, all of it is organized informally, there are…
Are you sure there aren't certain people driving these "informal" parties?