Collaboration

As a one-man-band outfit (in just about any industry, but particularly in any industry that has a strong creative element) there are significant competitive disadvantages.

1. Your standing in the business community.
   Most companies are reluctant to do business with small single-entity units as there is a possibility that the person doing the work will move on/lose interest/get another job. In computing there could be issues with getting someone else to pick up the reins of a half-completed project. There is just no redundancy.
2. Cover for rush jobs, sickness, even holidays.
   As a single-entity unit there is always the prospect of having either not enough work or having too much work. The problems associated with too little work are obvious, but having too much work is also a curse. Once you start turning jobs down that avenue tends to close and they probably won't approach you again, even when times are a little less hectic.
3. Cumulative experience.
   It's always nice to have someone in the company who knows what they are doing on a topic that you might not know as much about as your core skill. And, as someone who might know a bit about a topic, it's always nice to be able to pass something of value on to a co worker.
4. Objective viewpoints.
   Sometimes you can be working a little too close to a project to be able to see it's flaws. A co worker or project leader can often see mistakes made or the possibilities of problems ahead that are not necessarily apparent to yourself.
5. Your capacity to bounce ideas off co workers.
   Sometimes a good old-fashioned brainstorming session can really get the creative juices going. And, when you are stuck for an idea, just chatting about it to someone else can unlock possibilities that you hadn't thought about.