I don't either, but this is a "social media" site of sorts. Originally, you could leave reviews of business/products/public events, etc., but it has grown to add "friends" and discussions. I only dabbled in it on a very superficial level, and read and posted reviews.
When I do product research for stuff to use at work, I sometimes see those offers to review, friend, like etc the product or site-I always click the no thank you, or just ignore the prompt-it is obviously a way for them to sell your e-mail address and flood it with spam, at the very least...