Mistress M of S & M's Book Obsessions nails it.  

No random author, I'm not going to friend you on GR just because I mentioned that I like historicals set in Rome and you have a historical coming out set in Rome as well. We have 0 books in common and your book looks like it's that genre (slave fantasy) that I've just decided I don't usually like. I don't know you, and I don't want notifications about your book being pushed on me.

Oh, and come to think of it, no other random author, no I'm not going to download your freebie (thus bumping it up in the sales rating) to review it. Because I'm pretty sure you're using me to bump up your sales rating and hoping for 'soft' reviews, which, if you actually knew anything about me, you'd know wasn't going to happen.