As the title asks, why do some players switch between their melee weapons and their guns when it isn't necessary and if anything could be harmful to them because they'd have to play the equip animations?

I don't understand why getting those 2900 a piece phantom/vandal for your broke teammate doesn't even count a little bit in the stats of 'Avg combat score' when diffusing/planting of spike does. Like Today when I was playing a passive Sage...