The fallacy is that it is not properly understood that the "time constraint" is only one the sending end meaning on the thumb using end. On the receiving end, meaning on the head using end, reading a message of a word count of 70 is one minute different from reading a message that has a word count of 400.
So we are having these truncated half-conversations or 1/3 conversations believing it is the same thing or somehow even better. It is not and I am no Luddite but I do believe it truly is a fallacy and as such, it should be exposed in order to be understood in order to be remedied not by stopping to text message or use Blackberries but to understand there has to be more to complete an interchange of thoughts in full rather than just "brb" and "lol".
TTYL he he