Best in slot element for drone bonus damage

Why do people advocate that radiation weapons are best in slot for drone Zane mobbing?

For general usage, you want the drone bonus (cryo) damage to be on a weapon whose element covers the weaknesses of cryo. This minimizes elemental penalties between the 3 health types. Since shields are the only health type to resist cryo, that leaves two options: shock and radiation (kinetic as a neutral element is third). Looking at the multipliers (assuming cryo damage ratio of the anointment is 1 as it is today), radiation seems to be more level:

(Health/Armor/Shield)
Shock: 1.65/2.15/3
Rad: 2/2/2
Kinetic: 2/2.3/1.5

… but remember that non-maliwan weapons have a smaller damage multiplier for rad damage (.75) than shock (.8). Incorporate that and we get:

Shock: 1.32/1.72/2.4
Rad: 1.5/1.5/1.5
Kinetic: 2/2.3/1.5

Ignoring the DOT, radiation doesn’t even out damage a comparable kinetic weapon. On multi-bar enemies, assuming equal hit-points per bar, a shock weapon has better average raw DPS than a rad one in all scenarios except multiple health bars.

Obviously for Maliwan weapons, without differing gun damage multipliers, rad is a more attractive element. With either shock/corrosive to handle immunities or fire to really maximize health damage.

TLDR: why is radiation the prefered element for drone bonus damage? Only outperforms shock/kinetic in niche cases on paper.

That’s one of the issues right there. The DOT can rack up more damage than you might think, particularily with radiation (plus, the DoT ticks also help you re-apply your seein’ dead and keep you healed through salvation). And since cryo as an element doesn’t actually have a DOT, just a slowdown/freeze effect you’ll want an efficient DoT on another element to compensate.
Shock has the worst DoT in the game, with a duration of only 3 seconds (9 ticks of damage) whereas radiation has the strongest with a duration of 8 seconds (24 ticks of damage) plus an additional effect of being stronger against groups because enemies near their irradiated colleagues will take damage and enemies killed whilst irratiated will explode, potentially spreading the effect further.

Thank you. I overlooked DOT duration when considering this. The interaction of additional damage ticks would be sufficiently worthwhile to overcome 10-20% damage differences when considering QoL.

Numbers suggest it might still be worth preferring shock for biased runs like GT and of course a good roll of shock or rad is always worthwhile.