[AussieRacer]

The main "benefit" of DTC in the wet is you just keep your foot planted, or have a slight breath on the throttle. She'll step out of line a little, but won't do anything silly.

Have DTC off, and you'll need careful throttle control/balance to keep it from over stepping the mark. A quick step off the gas retards acceleration, which causes a weight transfer rearwards, which combined with the slowing of the excess rotation causes the rears to grip up and push the car the direction they are pointing. If that is different to the steering angle she'll tank slap like you experienced. DTC can only help so much with the parameters it is already aware of, so if you change the parameters on it (quickly off throttle) its actions may be thwarted.