It probably reduces people trying to get in their cabin early, just don't put cabin keys out till 1:30. Nobody steals them, there's no reason to. My only problem with the system is on MG where they have the lido soda machines, you cant use them without a card.
Edit: in some embark. ports they have you check in when you do the vaccine card check and don't have to visit check in at all. This is how it was in Galveston before 2020, straight from security to ship, now you have to get someone to check your passports.