Others have written about the downside to Ranked Choice Voting or "instant runoff" as it is sometimes called.
But the flaw in RCV isn't that some ballots get exhausted because people have selected candidates that are too "fringe" too high on their list. No, the problem with RCV is far more fundamental. It is a logical fallacy.
That fallacy is treating the relative preference of politicians as being on a continuum where the differences are differences of degree. As if the voter is ranking 80 degrees warmer than 70 degrees. And therefore, it is as if you are saying you'd rather have it be 80F outside for a pool day than have it be 70F.
But political preferences don't work that way. It's not that some candidates are "more acceptable" than others. We're not picking restaurants. Most people view their ballot preferences in more binary terms-- a list of people they find acceptable, and those they would find completely unacceptable.
Can you imagine an election in which NY state voters had to list "Donald Trump" as their 2nd-most preferred candidate? Or even third-most preferred? Many people would say that there is no situation in which they could accept having their vote count for Trump at all.
Yet a RCV system could very well end up doing that because it undermines the voter's ability to veto a candidate and include someone on a 'over my dead body" list.