>>in fact some clubs nowadays maintain that this is entirely the artist's responsibility<<

That is not acceptable.

If I book an artist, I consider it my job to promote it. Why put these artists on if you can't be arsed to promote it. Its a thankless task promoting, but its a job that has to be done.

If an artist has a website and mailing list situation, it does help as they can possibly generate extra income for themselves (if they are on a % of the door).