Auto body repair & detailing: Primer vs ?, factory paint, wet sanding

Question
I heard that if you sand the clear coat away from the factory paint, the sanded factory base coat is better than primer for your new base coat to stick to.  Is this true or ?

Answer
If you just scuff the clear coat with a 3M gray scuff pad and refinish from there is best. 3M also makes a scuffing paste that you use with water and scuff pad. Be sure to wash when your done scuffing your vehicle. If you sand off all the clear you will have areas where you go though the base coat and some areas where you go through the factory primer. It is hard to sand off just the clear coat but if you could yes it would be better than primer to paint and clear coat. Do not use any coarser than 400 grit sand paper and wet sanding is better than dry sanding.
             Thank you for the question !
             Ken