For the continuing education of Polter-Cow, and the shuddering flashbacks of others, the preferential voting controversy related back to Bureaucracy 2, when we were instituting voting for the first time. (There having been screaming arguments about whether consensus actually constituted the will of the people.)
Voting having been voted upon, people then began to wonder how voting should work. Preferential voting having been suggested, 500 of the most boring posts in the world ensued, explaining the illuminating joys of preferential voting and denigrating the awful confusingness of preferential voting. It was 500 posts straight of math and mathy-logic, and the universe was very nearly divided by zero before yammering about another topic was able to begin.
Anyway, it ended up not mattering really, since whoever proposes a vote is allowed to write the ballot, and can write whatever form of voting she likes. (I don't think we have had a preferential vote, due to the possibility that a percentage of the electorate would have an aneurysm and we might fail to make minimum turnout.) We have had yes/no questions; questions where you had to answer a number within a range which we then averaged; "if you answered yes to this, please answer yes/no to the following", and I think that is all the kinds of votes we have now had. Preferential voting is not specifically disallowed, but it sure is funny to invoke as a "don't go there! That was lies conversational DANGER!!!" item.
Sort of like gerunds, except the gerunds war was genial.