The intention is to (a) allow any sufficiently-sized group to elect an acceptable-to-them council member, even if they don't all agree on a first choice and (b) encourage voting for the candidate that you like best even if they're really unlikely to win a seat.

It has its flaws; the emphasis on #1 votes to avoid elimination is a major factor, and name recognition is as big a deal as in any election. Even so, it means that when I vote I can first list the newcomer that I like best, then possibly another one, but still support only the best of the incumbents if (more likely when) the others are eliminated.