If nobody understands, tell them!

The "all originals" rule is often a way for club owners to provide live entertainment without having to pay for a performance lisense, which grants public performance rights, and which then pays composers/lyricists for the use of their songs--though no one ever thinks about this, really, the performers who write their own material are getting cheated, because, though their songs are being publically performed, they receive no royalties--in some cases, it is also a hedge against paying union scale to performers--

In some circumstances, though, it is a good thing--like most other things in the business side of music, you have to make your own decision about whether it is good or bad for you, and move ahead--