Goalposts moving. Straw man building.
The claim is not "propaganda doesn't work!" or "targeted advertising doesn't work!"
The claim is that CA was not magic. If you target racist advertising at racist people, the predictable thing happens.
CA was pointed at Black voters and *didn't work*. It was pointed at non-racist white voters and *didn't work.*
If I say "Haitians are eating dogs!" that works on who you think it would work on. It increases their likelihood of voting.