I have done it both ways. With all ranged, and with 1 or 2 melee. Its definitely slower with melee vs taking all ranged. Also less prone to dps deaths and wipes.

Tornado phase is the issue here with melee, assuming MT takes Garuda and Suparna tanks NW, and OT picks up Chirada and the plume goes SE. Melee follow offtank to burn down Chirada, healers and ranged in one of the adjacent quadrants. With all ranged you can immediately target Suparna as soon as Chirada is dead no need for the OT to even pick her up off the MT. Now then if you have melee you have to wait for the OT to provoke Suparna and she has to waddle herself through tornados often moving slow sometimes stopping to slipstream, for every melee dps you have you are losing dps up time when she is being dragged across the room. On top of that it is easy for melee to die to wicked whirl and have to be very aware when it will come out and run away when it does, more dps loss.

Stacking all ranged basically takes out much of the chance a dps will die because they can just stand in their quadrant and not have to worry about getting hit by anything but friction which is easily dodged. Lets you have almost 100% dps uptime on the adds in turn giving you much more dps time on garuda. With melee there is a lot more waiting for adds getting into position after provokes.

Overall the easy way to do it is stack all ranged which is why people shout for ranged only.