Like any technique, anyone may do it. Few do it well.
Back-fists are notorious for breaking your hand if done improperly.
At advanced levels, "basic" no longer applies. It must be done right.
Nothing. Anybody can make a fist and swing. But that is not martial art. It's making a fist and swinging. It's unfortunate that a lot of people can not tell and don't know the difference between a "make a fist and swing" style and a martial arts style.
Anyone can "throw" one but not with real power, not without telegraphing, not without putting yourself in a position that will leave you vulnerable to getting hit especially if you miss.
Applying it with power without getting countered to a person that want to remove your head from your shoulders. Otherwise it’s quite simple.(This applies to every single technique)
Cant anybody throw that even a untrained person?