That is actually a good question. Self-assign is simply the ability to view a job on the MSCs website and assign it directly to yourself without the help of a scheduler. Companies like Market Force, GFK and Expert Solutions (aka CORI or Stericycle) are set up so an approved shopper can always assign their own shops. Some companies such Intellishop, Bare International allow a combination of self-assign and scheduler assigned shops, while others only have shops assigned by a scheduler.
Equal rights for others does not mean fewer rights for you. It's not pie.
"I prefer someone who burns the flag and then wraps themselves up in the Constitution over someone who burns the Constitution and then wraps themselves up in the flag." -Molly Ivins
Never try to teach a pig to sing. It's a waste of your time and it really annoys the pig.