Imagine a sea of microinstances. Wonderful little butterflies of small monetary consumption that flitter around together living peaceful, low traffic lives. Suddenly, the big bad train of web traffic comes and your little butterfly is terrified! Whatever will poor Mr. Butter do??
Luckily, Mr. Butter has friends. Alone they are weak but united they flutter fancifully. So when the tracks rumble and the big bad train comes they stand together, your butterfly passing off the load that hits him to his butterfly friends, the whole impact distributed. Together they will defeat the big bad train and any other big bad trains that come for his fellow butterfly friends.