A lot can be said about talking face-to-face with someone versus writing back and forth. Voice inflexion, facial expressions, and hand gestures are just a few of the non-verbal cues that can never come across in writing. Actually, let me amend that: they can never have as much precision in writing. Given some lightweight markup, smilies, and pacing, some of this actually can come across in writing, but it's certainly a far cry from what we can communicate in person.
Then there's the social factor. It's hard to feel a real personal connection with someone without ever speaking face-to-face. Again, this isn't a black or white issue. It's absolutely possible to become very close to someone without ever seeing their face, but it's going to take longer and probably require more effort than if you had the opportunity to have drinks together on occasion.
But for all of it's qualities, in-person discussions fall short on two points: efficiency and clarity. Let's assume a simple definition of efficiency as achieving a desired result with minimal waste or friction. Now, imagine instead of reading this article, I forced you to meet with me so I could explain my point. Also consider that while you've been reading for about a minute, it's taken me about 30 minutes (so far) to write it. So you'd need to sit and listen when I think out loud and try to make my point for 30 minutes.
Two things are happening here.
The first is that I'm wasting your time. I've interrupted whatever you were doing to hear me out rather than read this at your convenience. There's the friction. I'm also taking much more of your time than if I'd written my thoughts down for you. There's the waste. Communicating in writing is all about focusing on the receiver. It's more considerate. It'll take me more time to write this than it would to say it, but it'll take you far less to consume it. Considering I'm communicating to more than one person, my own additional effort results in the reduced effort of many.
The second thing that happens if I forced you to hear me out in person is that my point has been drowned out by the noise of my own rambling. Writing this article has forced me to boil my point down to the essentials, making my point as clearly and consicely as possible. Whether I've achieved that goal or not, I guarantee you I'd be much less clear if I tried to verbalize all of this on the fly.
All this is not to say that I never want to talk to a human being again. Far from it. If I'm looking for recreation or to make friends, being together face-to-face is hard to beat. But when I want to get work done, efficiency and clarity win. Writing wins.
The other benefit of written communication that I left out is the longevity factor. Say something to me and I'll forget it tomorrow. Write it down and it lives forever. This might not matter much when the goal is to have a good time, but it's huge in business.