Rabbits do not need salt licks or mineral stones. A good pellet should provide the salt and minerals a rabbit needs.
Too much salt means a rabbit will drink a lot more. While drinking is good, too much is not. It can lead to imbalances. The problem is that a rabbit may ignore the salt lick for months or eve years, then consume it in a very short time. A few licks a day might be ok, but you can't really monitor how much you rabbit uses it unless you hold it for them to lick. The same goes for mineral stones, but they can cause problems with too many minerals, some have lots of calcium which is not good for rabbits and can cause bladder stones and urine sludge.
I would just avoid them. No need for them.