I feel like the criteria minecraft.dropped:minecraft.air should either not exist or should do something.

I think this should either
1. Count the time you tried to drop something, but couldn't (because there was nothing in that slot) or
2. Just be a overall counter for dropped items (the same principle would apply for minecraft.used:minecraft:air, minecraft.crafted[...], minecraft.mined[...], etc

The second suggestion is, in my opinion (which nobody asked for), a better solution. Due to the fact, that this would open up new possibilities for people making minigames and especially map-makers.

PS: I do not think, I can attach anything useful. I hope everything is clear and understandable.