I really hate the idea of AC including putting up open posts. Just because I'd rather tag other people's posts than put up one of my own - if you put up an open post you don't know how many people are going to tag so you have to make sure you don't have too many threads on when you put it up, whereas tagging other people's means you can be more sure of how many threads you have on.

And, I don't know how much this is true, but I worry that it would mean everyone puts up posts and no one tags them.