I blame FPTP for the US' and UK's issues.
Dunno what's going on with you Aussies though.
My personal take is that social media has allowed a proliferation of fringe parties to gain traction.
Our two traditional parties have always been quite close to the centre, but these minor parties have forced them to move further left and right to stop votes leaking off to the crazies.
Leaves the sane and silent majority with difficult choices to make and means that both major parties are left trying to appease the vocal minority and the silent majority gets shafted.
A common thing recently had been a number of hung parliaments, both state and federal, with minor parties holding the balance of power.