If you consider they all want to develop craft skill.
Well, and everyone knows redundancy is important. If you have 5 guys, and one goes on vacation/quits/just isn't on at good times to interact very much you don't really have 5 guys. When you consider the coverage and activity you need for 5 guys to really run a fully efficient crafting team, it ends up being a lot more than 5 guys in most realistic scenarios.