Vote-suppression micro-targeting is more effective and harder to differentiate than traditional negative or positive messaging around candidates. They particularly target minorities who they know are unlikely to be swayed to one side, so the most effective strategy is to convince them not to vote. They often rely on the idea that not voting will "send a message" to those in power. In reality, it just makes the targeted demographics appear unreachable.

A team led by a researcher at the University of Wisconsin–Madison recruited more than 10,000 people across the United States — a group representative of the country’s voting population — to install an app that captured every ad they viewed for the six weeks leading up to the November election in 2016.

The study participants who saw the ads with vote-suppressing messages on Facebook were 1.9 percent less likely to actually vote in the election than people who did not see the ads...

“In fact, those minority users got the vote-suppression messages nearly 10 times more often than white people in white-majority counties in non-battleground states,” says Young Mie Kim, UW–Madison professor of journalism and mass communication and the lead author of the study...

While a 1.9 percent shift in the behavior of some voters is small, the researchers say, so were the margins of victory in many states in 2016. And, compared to white voters in white-majority counties in non-battleground states, nonwhites in nonwhite-majority counties in states with tight presidential races were about 14 percent less likely to vote. Extrapolated across the country for the 2016 election, the effect of the ads may have kept about 4.7 million people from voting.

Even a good politician whose goal is to help people can't help people if they don't have any power. That means winning elections. If one group votes at 2x the rate of another group, then enacting policy that pleases that group is 2x as effective at retaining the power needed to help all of the people when you can. That's why the groups with the highest voting rates are held as sacred across parties. You can never enact policy changes that will negatively impact them because you will lose power.