They should only give the checkpoint to those that have gone through the full 4 prior rounds. Not to someone the comes in and wipes like they do with the raids.
Even then the problem with that is that then the checkpoint can be shared. Say 3 people reach skolas legit. That's 3 saved checkpoints. 2 people switch characters. Kill skolas. Then one of the others switch back and boom another skolas kill rinse and repeat.
I doubt bungie would implement checkpoints in PoE.
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This is exactly what's being done for Crota, Templar and Atheon. I don't think it's much of a stretch at all, considering those fights are only slightly longer than skolas.