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 was inmortal, now D3, but now i have an new account, and i got gold 3, but, honestly People in gold,platinum, are WAY HARDER than diamonds, inmortals, they run and gun, and seems like it works. They do no sense stuffs, and it works, the...