That would largely be because they ARE a monstrous reminder of something you have done wrong - not to put too fine a point on it.

Unless the topic is about what to do about them, there isn't really much purpose in discussing them. They are what they are - we can't change that. Side bars like this one are fine and useful, but other than that what's the point? If it's in the context of, "Hey, kid, wanna look like this?" then that's useful. But I don't have to show my stretch marks for THAT warning to be effective!