I've always had a sponsor and I believe one needs one to work the steps with a sponsor for the following reasons:
- addiction is an isolating disease, so by sharing ourselves with a sponsor we are coming out of isolation
- the only people who have never sort guidance and went it alone are folks like Aldof Hitler (excuse the spelling) and look what he did
- justifaction comes easy to us so we need someone to see through our BS
- wise people learn from their own mistakes BUT wiser people learn from the mistakes of others
- a sponsor has a different 'take' on our lives as they have no emotional involvment in it or investment so is able to point out/suggest things we may not see/understand
- we get to expereince what it is like to have someone love us and accept us unconditionally
- we get something concrete to pass on to others
I can probably think of a ton more too.