Why use Rain of Splinters?

I'm running a Freezing Pulse/Ice Spear totem build and I see on PoE Ninja a lot of them use Rain of Splinters (+2 projectiles, -30% totem damage)

But they already have awakened greater multiple projectiles. My understanding is that additional projectiles don't add up any more damage on a single target. If you already have 7 projectiles, why is it so good to go to 9 projectiles -30% damage? 30% seems like a really big drop. Am I missing something here? How is +2 projectiles worth losing 30% of your damage? (example: https://poe.ninja/builds/settlers/character/Poeaccount26/HoldingHandsWithYou?type=exp&i=1&search=class%3DHierophant%26skillmodes%3DTotem%26items%3DSelf-Flagellation%2CThe%2BAnnihilating%2BLight%26sort%3Ddps )

Thanks.