Even according to the liberal FairVote group pushing for Ranked Choice Voting, as many as one in three voters may only list their first choice of candidate. This means that in the event of an automated instant runoff, all of those votes are literally thrown out and have no impact on the selection of the winning candidate.
According to reports from Utah, “…officials have reported multiple problems with enacting the state’s RCV pilot program in county elections. Because of the complicated nature of the tabulation process with RCV, many ballots have failed to be counted. For example, 58 percent of ballots were either discarded or spoiled in 2021’s Genola City Council Race, often because those voters failed to rank a second choice, according to the Election Transparency Initiative.”