There is no need for checkpoints in Savage. That being said, V4S and V8S have checkpoints once you unlock the “Savage extra” portion of their fights (i.e., once you kill Exdeath in V4S and successfully get to Neo Exdeath, the instance will restart with Neo present for the remainder of the lockout; same thing with Kefka/Winged Kefka in V8S as far as I am aware).

If people are joining clear groups that have no business being in there (i.e., the party is listed as a clear party for those who have been to or seen enrage multiple times, and someone joined with zero experience in the fight), then it falls to the party leader to enforce the rules of their PF. V5S is not long enough, nor difficult enough, to warrant checkpoints within the fight. If people aren’t pulling their weight and/or causing multiple wipes to the same thing over and over again, the party leader needs to either remove them, or you should bounce and find a different PF with a leader that will enforce their PF rules.