Does a Farmer sign his produce?
-- a Baker sign her cakes?
-- a Dentist sign her crowns?
-- a Professor sign his lectures?
-- a Scientist sign her research?
First of all, from more than a decade of working on a college campus can say, with all certainly, that a scientist most definitely "signs" his research. Publish or perish. Fill the vitae. There is nothing in either academia or research, nothing, that is not claimed. I'll go so far as to say the same thing for professors and lectures. It may not be an actual "signature", but make no mistake, it's stamped, copyrighted, trademarked with the names of the creators. They all want their credit. There's no difference.
As for dentists and bakers, there's a world of difference between those two professions and artists. First and foremost, a dentist is a craftsman, not an artist. He/she is not creating art, but filling (pardon the pun) a dire need.
A baker, while some, in the extreme, may create something very close to art (extreme cake maker or confectioner), makes a product that is consumable. Disposable. It's not meant to be kept nor displayed, but eaten. Therefore, a signature, which one could argue may be deserved, isn't really relevant.
The bottom line, as I see it is that you seem to confuse art with commerce. Creativity with necessity. Meaning with retail. In your view, there is no difference between an impressionistic watercolorist and house painter, or a university lecturer and performance artists.
Art is not a commodity, it is a creation from the heart and mind of an individual. In it's best form, it has meaning beyond it's mere physical manifestation. If you cannot see the difference, then there's nothing more left to say.
