Explanations For Injury

Can anyone explain to me how when people say they injured themselves from light jelqing or stretching etc, how they didn’t first hurt it masturbating. I know they are different in a way but it’s confusing as to how they didn’t have hurt it during an intense masturbation. It seems like it’s a predisposition and doesn’t make sense how 20 light jelqs did this. I’m a newbie and I’m trying ti filtrate fact from fiction with these cases, so I can PE without yhinking I’m gonna hurt myself. Hope this is in the right thread