A nitpick: in a normal election, half of the Senate faces election, so 6 per state. It's only double-dissolution elections where all 12 face election at the sa

A nitpick: in a normal election, half of the Senate faces election, so 6 per state. It's only double-dissolution elections where all 12 face election at the same time. In those scenarios minor parties and independents are much more likely to get elected, because the quota is halved. Voting above the line works basically fine. What happened is that the major parties were too lazy to discuss things with many minor parties, who then went off and arranged their own preference deals.