So, in looking at some fairly basic German conversations, I came across the following:
Hallo, wie heißt du?
Ich heiße Susanne. Und du?
Ich bin der Martin. Und wer ist das?
Das ist meine Freundin, Anne.
In another question, the accepted answer for such a use of the definite article precedent to a person's name is that this is a "usage associated with the south of Germany more so than the north."
That is fine, but what I don't seem to understand is why use it in this situation at all? I could get behind it if there were more than one Martin, and you were pointing out the Martin to whom you are referring, but in this case, the implication is that there is only one, so what is its usage here?