Exactly. They can suggest whatever browsers they want. Much like how Google suggests Chrome whenever any page with their logo loads. It's not like Facebook is saying if you aren't using on of these three browsers then we can't help you.
So the "you're" bit is vacuous. They don't mean your browser. They don't [functionally] mean any web browser. The page makes a statement, but we need to interpret that statement IRRESPECTIVE of our considerations of how it is generated/produced.