Every time I speak at a writer's conference, I teach my students how to submit their work to an agent or publisher. I have a list of DOs, and a list of DONTs. Many of them think it's unfair that I might reject those who don't conform to the prescribed process. After all, the book might be good, and a less-legalistic (and presumably more virtous) agent might snap it up and I will miss out on a great opportunity.
Sure, that could happen. But I still need to follow a screening process, and I can't help everyone.