Is the so-called “winner-turns-loser” or “monotonicity” issue have any real-world significance?
No. The “monotonicity criterion” has received an inordinate amount of attention by IRV opponents on the Internet. This is an arcane criterion with almost no real-world significance. As with traditional two-round runoff elections, it is conceivable in certain unique scenarios, that if enough (but not too many) voters were to switch their first preference from their favorite candidate to their least favorite candidate, that this least favorite candidate could be changed from a winner into a loser, and their favorite choice could go from loser to winner. However, simply adding new first-preferences for a candidate can never cause the candidate to lose — IRV is monotonic as far as additional votes are concerned. It is not the additional vote in favor of a candidate that can cause the candidate to lose, but rather the change in relative support among the other candidates resulting from a vote switch. It is the switch away from another candidate, whether that switch be to the current winner
