Why should you bother to add either? Well because when I post something out, it usually takes up to an hour or two for BoardingArea's automatic systems to pick up my new post. For something like mistake fares where time is of the essence it's much better to hear it sooner rather than later.
Also I tend to share more of my travel photos from my travels on the Facebook page as that has a lighter-hearted tone than the blog. I hope that's enough to convince you to join!