Smoky bandit said:.use a butter knife to mix....do not kneed at all..the more its mixed and kneeded...the dencer it will be
Yep, SB has it right, it is the same principle as scones, if you work the dough it develops the gluten, which is good for bread, but not good for damper and scones which depend on the baking soda to make them rise.
Also, make the dough fairly soft, which assists with the rise as well as making the product less dense. The butter helps make the finished result tender too.
Apparently the old timers used to resort to some interesting methods when baking soda was not available. I read years ago of blokes putting Eno's Fruit Salts in to rise the dough, but can't find any references to it on line!
No doubt the baking powder and butter free recipes were used when all that was on hand was flour and a bit of salt, and the main concern was simply getting feed, even if you needed sharp teeth and a strong jaw to eat it. That said, the ability to make good damper was highly valued and a mark of a good bushman.