> the destination is separate header data that is used in routing and not considered part of the message body
Right but how could Twitter have put data into the separate header in an SMS message? They can't do that. Hence the 140 character limit (the 160 hard maximum for them being able to put into a message and then minus 20 characters for commands).
Possible, but would make the user experience worse as then they couldn't reply to the text, if they wanted to respond (send a tweet back, etc.) they would have to go out of the message, find the Twitter number, open it up and reply there.
Right but how could Twitter have put data into the separate header in an SMS message? They can't do that. Hence the 140 character limit (the 160 hard maximum for them being able to put into a message and then minus 20 characters for commands).