That is probably true for people just starting out, but for many people it will be a number of years of holding a mortgage before they have spare money to start paying extra off. Therefore in many cases (such as my own) there is already some equity in the house which can be drawn down in a real emergency. In my personal circumstance, I have been making extra payments on my mortgage for the past couple of years and the advisor has suggested I now switch to putting that money into super. In saying that, I can't get what I have been told all my life out of my head and have decided to continue overpaying my mortgage with 25% of the extra money and the other 75% I now put into super.
NWM