"It can cause more ballots to be thrown out (uncounted) if voters don’t follow directions clearly."

With single choice plurality voting, ballots are "exhausted" after the first vote. With RCV even with exhausted ballots the votes in the final round are greater than would be cast in a typical single choice runoff election. RCV allows a voter to select the preferred choice without worrying about a wasted or spoiler vote. The only significant complaint about implementing RCV is the cost of educating the public on the voting process and acquiring certified equipment. The NYC primary results will be delayed because of accepting vote by mail ballots postmarked on election day.