That’s not the aim of those campaigns
They want to turn away potential voters for that candidate and also rally support for their side
Basically if the voter is likely to vote for a candidate they want to blast them for being terrible and bad with the aims that people won’t vote for that candidate, not necessarily vote for their preferred candidate
If the person is likely to vote for the candidate the ad campaign is backing they want to lionize the base to turn out to keep the corrupt, ammoral, completely abysmal candidate from winning the race