Photographer names on images, why?

[iamdlewis]

I've seen that used on proofs when a wedding photographer sends proofs to a client to choose images for an album. The idea being to make them usable for choosing images, but not usable to print - if they don't do that, people don't buy prints from the photographer - they print the proofs.

I would expect watermarks on proofs but on final images it seems silly to me.