I can't completely follow the argument, but I think Arrow's is mostly used to counter the "utopians" (roughly; people who argue that one system is Inherently Un

I can't completely follow the argument, but I think Arrow's is mostly used to counter the "utopians" (roughly; people who argue that one system is Inherently Unfair(tm) and the alternative is Inherently Fair(tm)). You're replacing one flawed system with another flawed system, so you should not argue in terms of the presence or absence of flaws, but rather argue why one is better than the other. RCV can still have outcomes that a majority will disagree with, but it should be less common than FPTP, and also make third parties competitive in practise. That may be better than the old system (and it also may not be), but it's not going to resolve the fundamental tensions of representative democracy.