When you get to reading, you will find that the brine shrimp normally reproduce live born, and cysts are produced when conditions are not good for their survival.
If food or water conditions are not suitable, they DO produce cysts and that is what we buy in the stores in cans, tubes, or bottles.
In nature, the cysts hatch and grow to reproducing adults again once conditions return to normal again.
Decapping the cysts is basically a bleach treatment that changes that outer cyst so that only a soft membrane basically is left to contain the egg.
Advantage would be ridding the cysts of the high bacterial problems they are known to have, and some find that decapped hatch faster with a higher hatch rate.