In real life, things done when a person is young are often forgotten with time, and the way the brain works is that time lessens the importance of a memory, so even if it's not completely forgotten, the memory is fuzzy and considered inconsequential.
On the internet, everything is as fresh as this morning, forever. No longer do we have "do you remember when so-and-so used to say that stupid stuff, boy have they changed!" Now it's "look, here's a link to so-and-so staying stupid stuff, now we know what they really think!"
The idea that once something is in the public it should remain there firmly embedded, forever, makes sense on the surface, but definitely seems to break down when examined closely, in my opinion.
