Posting up, and commenting on, pictures to a website can be fairly time consuming.
There are image packages that allow everyone to do this, and everyone to comment, like I have put in place for the AOMCC:http://www.arielownersmcc.co.uk/members ... /index.php
(note: This implementation doesn't require an account to post into existing directories or comment BUT it's already behind the AOMCC user/password)
The problem with allowing anyone, publically to post stuff up is the amount of spam that could happen.
This is why forums have captcha and question/answer during registration AND admins to clear up the inevitable mess.