I agree you can read faster than listen, but I just don’t buy that typing is faster than talking though, not for conversation. When you talk, the speaking and the listening are overlapping. Sentences are generally understood before the speaker even finishes saying them. That’s doesn’t happen with text chat. When you type into chat, the communication is serialized. There are reasons a group sitting together might use devices instead of talking, but I find it hard to believe that efficiency of speech is really a primary reason, unless you’re talking about sharing media like sources, images & movies, quotes, references, code, etc. for a group project.