Minor parties don't 'fracture' the vote in the lower house because of the way the preference system operates there - more options usually just means more opportunities there. In the upper house, the group ticket system does have some problems, especially when, as happened this election, the preferences are decided based on deals made between the parties rather than based on the policy of the parties or candidates receiving the preferences.

As long as the parties allocate preferences in a rational way, even the upper house system will normally not run into problems because there are more candidates. Hopefully the ALP and Democrats will have learnt their lesson on this.