I'm puzzled. The conference that I attend makes NO REQUIREMENT that one submits a paper to the proceedings. In other words, I'm not obligated to submit anything to the proceedings. Are the conferences you attend REQUIRE such a thing? How can they enforce it? After all, the conference is over and all you have to do is not submit anything. They can't force you to write something, can they?
It isn't true that no one reads conference proceedings. Until recently, the accelerator physics field relies A LOT on conference proceedings from various PACs , LINACs conferences, and AAC (Advanced Accelerator Concepts) workshops. In fact, the accelerator community has created a JACoW page
where conference proceedings from this various conferences are centralized. In fact, these are the quickest and most up-to-date means of getting information from various parts of the community.
Furthermore, it isn't true that all conference proceedings are not refereed. I've been to several in which I had to referee conference proceedings.