IMHO the fact is that anything you write or the pictures
you uploaded will be archived as long as there is
Internet as we know it.
That perhaps doesn't sound too bad but, almost anything
can and will be taken out of content by some people.
Your views and opinions of today will most likely be
different in 5 or 10 years. If you post in a forum under a
username you are granted a great deal of anonymity,
however doing it on Facebook and co it is all linked to your real name.
I could go on and on but these are the major negative issues.
Just my $0.02