Why SMS signatures?

I am baffled as to why SMS (text messaging) signatures exist. Dad and Danny are the two people I know who consistently use signatures. After each text I receive from Danny it says after a line break, "Your Local Devil." After Dad's it says, "Paolo." (Imagine the confusion that causes me.)

Personally, I think SMS signatures are a bit redundant. I mean, I know who the text is from. That's why I have a list of contacts in my phone. Duh. But I also have a signature in my work email, and my name is in my email address, so...

I discussed this with Scott, who just taught his dad how to text message. He said it was a catastrophe at first because his dad was using his mom's phone. His mom had previously put her name in the signature and he never changed it. Scott was baffled every time he received a text that said:

"WE GONA DO SOME FISHING TIS WEKEND?. Cassandra"

Notice the all-caps. Typical sign of a digital immigrant.

According to Nielsen, American teenagers sent and received an average of 2,272 text messages per month in the fourth quarter of 2008 β€” almost 80 messages a day, more than double the average of a year earlier. Surely these teens aren't using signatures. How many times would friends and family need to see their names in text?

Am I ignorant to the value of these or right for criticizing the unnecessary John Hancock?