I'm guessing by "true love" you mean the romantic kind. I believe that romantic love is required to not just be platonic. If you guys never met, then you would only love the idea you have in your mind of the other person. And there is soooo much about them, that you'll never know. People underestimate how true and important the saying "smell each other" really is. Also, online, even in video chat, you don't properly get most non-verbal communication.
So, yes, true romantic love can start on the internet, but it can never remain there.
No, I don't think you can fall for a person you know online, you're falling for an incomplete idea. Maybe you can fall for their character, at least the parts you can see online. But it's not complete, it's not real real. We are human. We are not just mind or spirit. In fact our body is what gives meaning to what we do. Don't underestimate that. So I'd "recommend" falling after you've actually met :joy:... I know we can't control this, we'll still fall anyways... But keep in mind that what you have is not complete...