Aircraft accidents are caused by a whole series of events and situations conspiring together - like the model of the holes in the cheese lining up to create the accident.
I see low experience as one of the holes in the cheese. Yes, I agree, experience is not everything especially if the selection and training is good BUT it IS a significant factor when it comes to stacking the odds of having an accident.
Good judgement (often) comes from experience and experience comes from bad judgement! If you have spent a significant time in the RHS seat you have probably seen one or two weak judgements which can teach you how to stay out of trouble!
Would you want your brain surgeon to be operating on you immediately after basic training with no supervision?