Change how <100% drop rate items are given while in a party

[ItMe]

It would change the overall observed drop rate. If SE sets the drop rate at 5% it's never going to be exactly 5% because they don't use streak breakers or anything to guarantee it. But the more attempts there are the closer it will get to 5%. This change would reduce the number of dice rolls resulting in more variance between what SE sets the drop rate at and what the actual drop rate among all players is.

Say SQEX implements OP's idea
If I am in a party with my girlfriend to farm memories, and we farm 40 FATEs, that's 40 "dice rolls."

Say they don't
If I am in a party with my girlfriend to farm memories, and we farm 40 FATEs, that's 40 "dice rolls" for each of us.

There is no change.
Either way each player gets 40 dice rolls.
The law of large numbers will work the same wether I'm in a group or not. If we're apart it's not like we observe 80 rolls because no ones rolls are affected by anyone else's.