Sure you can feed chicks if you like smelly runny poop
As far as feeding wild caught rodent the risk is DEATH aside from parasite the danger here is that the rodent since you do not know where it has been could have got into rat poison which typically can take up to 3 days to kill a rodent, obviously not the kind of thing that is recommended.
With some feeder their is also a risk factor to keep in mind, while captive bred rats and mice are fairly docile (rats more than mice) other small animals are not, Hamster are VERY aggressive and have teeth that are longer than those find on other rodent.
Gerbils are like a drug to BP sure you can feed them but switching back from gerbils can be hard if not impossible and again not recommended unless of course you can guarantee that your animal will be with you for the next 30+ years and that for the next 30+ years you will be able to feed gerbils weekly which after a while might become very expensive.
Anyway in conclusion BP do not need variety they need a steady diet that works.
Ball Pythons are not like any other snakes, they are more picky than the average, and feeding variety is likely the best way for them to become even more picky and refuse food.
With BP you are best of feeding prey that are easily accepted and readily available to you and maybe the future owner should the animal change hands at some point.
Now Boas and many other snakes it's a all other different subject as many snakes are garbage disposal that would eat anything as long as it's warm enough.