I think he posted that more as a joke than anything, and he is part way correct... there is no way to learn everything on your own, I know you can learn to fly purely on a sim because I know somebody that did it, but if an unforseen event happened and the plane crashed is the sim going to show them how to fix the plane?? Say they are out flying one day in the middle of an open field that they didn't know lies right near a club's field and somebody from the club flying a turbine jet suddenly loses his radio because of interference and the plane crashes into spectators, he is going to be paying for lawsuits out the nose when he could have payed a little more money and get AMA membership and instruction from somebody who knows what they are doing. Also the servo reversing thing is a good point, I'd imagine any instructor would teach you to pre-flight your plane before you give the engine any throttle, maybe you don't have this drilled into your head on your own, if you accidentally hooked up your aileron servo's backward you won't notice until the plane rolls the wrong way, and unless you have amazing reflexes you may not be able to prevent a crash. Throttle servo, no problem... hook that baby up the wrong way and then flick start your engine, then continue to see how easy it is to fly with one hand.

I'm certainly not saying everyone is imcompetent and moronic, but some things you just don't know if you don't get proper flight instruction, its not your fault if you crash your plane into someone because you didn't know someone near you was using the same frequency because you didn't know that, but you could have known.