Because you don't want to get an email every time someone hits <enter>. The UI is very different, an email client would have no idea how to treat these one-lin

Because you don't want to get an email every time someone hits <enter>. The UI is very different, an email client would have no idea how to treat these one-liners and you don't want to have your inbox flooded with messages. Also, people just don't seem to care what protocol is used, and email is massively inefficient for that.