The reddit post is complaining that these companies aren't really looking out for the candidate, and to be honest I don't know what OP expected. Head hunting is a business, they're not in it to find you the job of your dreams. The main advantage I got from using headhunters like Selby Jennings (I didn't use Selby) was that they got me interviews with a number of firms that I would not have otherwise considered. Afterwards, I decided for myself whether the company was a good fit and just ignored the headhunters.
Just remember, they're not your friend and they're not looking out for you. It's a business, and if you don't meet their criteria (i.e. you're going to take up too much time and not get them the commission they're looking for) you're going to get dumped fast