He/She vs. They

I know that Oxford Dictionaries thinks that using he/she instead of their is "rather awkward," but I just cannot bring myself to do it. Using the plural form makes no sense! In fact, maybe I'm just dense, but I recently had to read and re-read a Facebook notification for this very reason:

So and So also commented on their status.11:00am

The use of "their" totally threw me off. Plus, shouldn't Facebook know whether So and So is a he or a she? Come on!