Your not stepping on anyone's toes......the topic of bonsai soil has been a long and hotly contested one. Its a kin to the argument what came first the chicken or the egg....you can debate it forever.
I think...and John can correct me if I'm wrong... what he was referring to is, you being so new to bonsai, have yet to explore all the avenues available to you in regards to soil. Being a long time veteran of the bonsai wars he, as well as others, have played with just about every ingredient for a soil out there and is in his own charming jet lagged way
Growing a tree is one thing. Growing a tree with optimal performance is something all together different. We as bonsai growers/artists have a finite time to achieve results. So growing in a medium that allows a tree to survive is fine...but not necessarily the best way to achieve the results your looking for.
If you have not read this ARTICLE I suggest you do...it gives good information and expounds a bit more on what I'm trying to convey