When talking about argument against RCV, you'd need to come up with a way to create a "spoiler" effect.
While it's trivial to create a spoiler in the current system ( Bush v Gore v Nader ), trying to create a spoiler in RCV is much much harder. Go ahead and try. Then compare that to what would have happened in the current "one vote" system. You can easily see that RCV is clearly an improvement and makes it much harder to have 3rd party candidates spoil the election by stealing votes from the most popular candidate.
While it's trivial to create a spoiler in the current system ( Bush v Gore v Nader ), trying to create a spoiler in RCV is much much harder. Go ahead and try. Then compare that to what would have happened in the current "one vote" system. You can easily see that RCV is clearly an improvement and makes it much harder to have 3rd party candidates spoil the election by stealing votes from the most popular candidate.