As someone who is into history and recreating some aspects of the past, I can totally see that baby led weaning would have been the way to go hundreds or a thousand years ago. Basically with limited equipment, supplies and just about everything requiring human labour to do, I just cannot see a viking women, for example, pureeing food when she has to get the weaving done, the geese fed and all cooking done over a fire. If a bubs cannot hold the food easily themselves, then I doubt someone would have had the time to spoon feed them and then deal with the washing that pureed foods create.

There are some cultures that do feed their babies something called pap from an early age, but I do not know much about that.

With regards to soy it is best consumed in the format that the Asians do (tofu etc), it is the westernised soy that is the main problem. This processed soy is added to so many foods these days, that we actually eat more soy than they do in Asia.