Was hoping you'd drop by and clarify that - makes sense. I think people should be utilizing beneficial microbes regardless of their style of gardening...You have to use extreme rates of synthetics to kill microbes. Your plants would die first. I believe the myth comes from agriculture when only synthetics are used in cropping. Natural microbes need organic matter (carbon) to survive, and they will deplete that if only synthetic nutes are added to the ground all the time. Then, with no food source colonies will be depleted. So it isn't that synthetics themselves kill, it's the fact that microbes starve out if there is no organic matter or carbon (sugar). Not all bacteria will be affected as some will eat synthetics as well. There are even species that eat toxic waste.
About bacteria that can eat toxic waste, quite interesting, I know there are also strains of fungi that will thrive on various forms of toxic waste as well. Cool shit.
If anyone's interested... The book Mycelium Running by mycologist Paul Stamets has some righteous info and concepts regarding this; using fungi/mycelium to rebuild damaged/polluted ecosystems and such.