I see flirting as banter to make sexual/romantic intentions known.

That’s basically what it is. It’s not there to make someone develop feelings, it’s a way to safely make your feeling known and see if they are reciprocated. It’s basically lowering the risk of rejection, if the feeling isn’t mutual and you don’t get a response you can just write it off as a harmless flirt. If (s)he flirts back you can dial it up a notch.