Thank god, group voting tickets was so dumb.
Personally I do think there should be a minimum number of preferences you need to fill out. It forces parties to be clear on who they would like you to preference on their how-to-vote cards. Which is one extra piece of information voters can use.
In a Melbourne Council election, the incumbent party preferenced a party called "rip up the bike lanes", so I could immediately decide not to vote for either of them without even needing to discover news articles or policy on the topic.
If you're preferencing a party like that, then I know you're stupid and don't deserve my vote.