RCV helps prevent a relatively unpopular candidate win by splitting the opposition vote. Lets say there is a region which we say is 80% moderate and 20% "extreme." 80% of the people definitely don't want the extreme candidate to win, but lo and behold 5 moderate candidates run but there is only 1 extreme candidate. All 20% of the extreme voters vote for the one extreme candidate, so they get 20%, and the moderate vote is split amongst the 5 moderate candidates equally with 16% each. Under our current voting system the extreme candidate would win, because they got the most votes, even though 80% of the population don't want them because all the moderate vote was split. With RCV the least popular moderate candidate would be discarded, votes re-allocated (to one of the remaining 4 moderate candidates because remember the district is overwhelmingly moderate) and the process repeated until someone gets 50%. In this situation the winner will not be the extreme candidate because they were ranked last for 80% of the votes.