This is the silliest claim about human communication I've read in a long time. As a writer, Manjoo may be uncomfortable letting others see his communicative sausage being made. But before teletypes and their successors, "normal conversation" — face-to-face conversation — was — still is — all hesitations, false starts, disfluencies, failed attempts at humor, misheard words, losses of attention. That's what we are, that's how we work. We perceive, interpret, and think as we talk, and a lot of that is trial and error.
Manjoo complains that instant transmission of typed characters makes the typist "self conscious." Translation: I'm used to hiding what/how I'm really thinking when I communicate online, and I feel uncomfortable coming out from behind the curtain.
Answer to comments: What Manjoo wrote was at best a unwarranted generalization from his personal reaction to the feature. He made an empirically false claim about human communication; even it the claim is charitably interpreted to be only about typed communication, he cited no empirical evidence about the alleged corrosiveness. Why did he feel the need to make a sweeping generalization, instead of honestly reporting his own experience, and that of others he interviewed, and let us draw own own inferences? The disease of the current 24-hour punditry cycle is an escalation of instant assertion unsupported by evidence to demonstrate the pundit's manhood (how's that for a sweeping generalization?)
Much before the BSD talk program, there was the TENEX talk command that had the same character-at-a-time behavior and may have been the first such program I used. Personally, I didn't feel it corroded my ability to communicate, but I won't turn that into a general claim. I was using Wave editing a document a collaborator recently, and the immediate feedback was useful to what we were doing, especially the marker that showed where he was editing.