Because if it's on the talk page, readers
won't come to it through the
search box and think, "Oh, look how stupid this encyclopedia is, they
have an article on a ridiculous subject like that". Isn't that
basically why we delete articles?
If someone is searching for an article on the subject, they aren't
going to think that, are they?
As for why we delete non-notable articles - it's a controversial
subject. There are plenty of people that think we shouldn't. My main
reason for supporting such deletions are based around consistancy - if
we have an article on one band that's never released anything, we
should have articles on every band that's never released anything,
otherwise we have systematic bias. I don't think we delete them to
stop people reading them and thinking badly of us - if they've found
the article, they are probably interested in the subject.