In the age of Facebook, blogging, and all other social media sites, many things that are posted, seem to have a life completely of their own. That is to say, once something is posted into a public forum, the person that first posted it, no matter their intent, has for all practical purposes, lost control of that posting, which can often be re-posted, commented upon, edited, changed, and spun into an entirely different direction, without anyone's expressed approval or permission. To a certain degree, that might be okay, if such a posting was merely a 24-hr posting, or had a relatively short shelf life, but some postings and re-postings, are especially resilient and because of that, they can create embarrassment or even far worse for those that are posted upon, with nary an end in sight.
Additionally, it is one thing for those that are in the public eye to be commented upon and to be posted upon in forums of all types, but those people are often well compensated as well as being consciously aware that in being a public figure that to a certain degree, they are living a life within a fishbowl. On the other hand, most people are relatively unknown, and reasonably circumspect, of which, virtually all of those people, do not have an interest in being publically embarrassed or publically scorned, especially when they have no recourse to delete the post, or even to make an impassioned defense.
So too, there are things done in public, in which some people are only too willing to post such, whereas others within that same group, would prefer not to have that posted, whatsoever; but rather would prefer to remember those events through their memory or their own un-posted remembrances via their personal pictures or video. The problem with social media posting in general is that the consequences as well as the appropriateness of things posted, are often not fully taken into account, or even not taken into account, whatsoever.
It is one thing, for people to get together and to remember moments, good and bad, embarrassing or not, and talk about them; whereas, it is an entirely different thing for someone, especially someone that isn't really one's friend, to have the ability to bring up posts of things about someone else that aren't really relevant to the present age, or should be left alone and forgotten, but instead they insist upon repeating these posts, in a manner that humiliates or shames another person, again and again, without end.
All of this would seem to indicate that social media sites need to design into their websites, a function in which the person that initially posts has the exclusive control of that content, and that those that copy and re-post upon it, are only able to do so for a finite amount of time, before that copy and all other copies so produced, are erased and eradicated. This seems to be a fair and reasonable way to control posts, especially posts that have created controversy or trouble, so that these posts do not live on forever -- especially within that public forum, as well as to preclude certain others from having the apparent right to be unnecessarily mean and vindictive, as well as being a prudent protection for those that simply suffer from poor judgment.