Notice again how I did not say that I owned or had ever flown a plane. Watching people flick start planes and reading stories of people getting hurt by props is enough to speak on their danger. Also the knowledge of a blade spinning at high speeds is enough to say that it is quite a dangerous thing to do, we don't playfully toss knives around in our kitchen because it would be a dangerous thing to do, the same as a spinning prop is dangerous.
I recall reading a story on these forums about a guy who started his plane then walked behind the flight line with his plane running, and the poster expressing concern that he doesn't like the idea of a spinning prop behind him in the hands of someone who obviously was running quite short of common sense that day. Whoever posted that was either an experienced flyer or somebody who happened to be standing up at the flight line for absolutely no reason while planes were being flown, and most likely he was there for a reason.

I need not experience these things myself to know of their existance, and again, I have never claimed to be a flyer, nor have ever said anything that would allude to the fact that I have done it.