Carol doesn't touch on this topic, but I thought I may mention that I’ve read that Facebook tracks all the visitors to your site and your Facebook page, and then promotes ads to them. So for example, if you own a store that sells furniture, Facebook will show ads to your visitors for your competitors' furniture stores.
In essence, you're helping Facebook’s advertising executives and your competitors by using Facebook. Think about it: how does Facebook make money? By advertising. By advertising what? By advertising what your competitors pay to advertise.
Which leads me to the next question: why would one want to use Facebook as their primary site?
I've asked Carol this question and will report back when she does.
I may add that there are a lot of options for setting up a website for free. (Carol's article doesn't mention other free website options.)
Stores can use Bridge as their primary site for free. Bridge doesn’t promote your competitors to your customers. Nor does it sell your data like Facebook.