There is nothing about something being "natural" that makes it inherently safer. Indeed there is nothing that is not natural in fact. Wood ash soap is no different than any other soap you may buy in the market. It only differs in the way that potassium hydroxide, that is used to make soap, is obtained. It doesn't matter whether you obtain potassium hydroxide from wood ash or other industrial methods, it still is potassium hydroxide! Of course in older times burning wood was the only known method of obtaining potassium hydroxide. It doesn't mean it's the best method not does it change the overall outcome in any way.

You seem to be taking a diss at science. The point of science is to learn more about things, whether they are old school or modern. Science does not discriminate. People of course bluff in the name of profits for their own gain, but if you do not have knowledge about the things, you won't be able to call out the bluff.