You cannot blame the beginner for that, but funny enough beginners in karate are told not to go too fast in hitting, because they have no control, they end you belting people.
I had been training on bags only for a long time,. when I went to the dojo I lost the ablity to pull. I was not hitting remotely full power more like 5% but it was still hurting people.
I did it to my son who is only seven I caught him on the chest, luckly it was just a glance but I could of hurt him bad.
My problem in aikido is using to much strength instead of techinques, that of course its a beginners nature, and one cannot be blamed for that.