I heartily endorse the idea that MobileRead is for people who use any of many different platforms. It doesn't follow that content on it should be limited to the least capable ones.
Note, please, that I asked my original question because the PRC format was the only format accepted by the only category under the description: "iLiad Book Uploads: Share your e-books made specifically for the iRex iLiad". I now understand that this is a bad description--that the link is really to another category. What I fail to see, however, is why there shouldn't be a category that follows the description--books formatted specifically for the iLiad.
My heart goes out to people who are trying to read books on cell phones and PDAs. I'm glad that somewhere there are folks wrestling with the problem of how to make text readable on them. But I'm afraid that I don't have a clue about how to do this, and I have no desire to learn. Perhaps if I were a better person, I'd put aside my own preferences and work for the "greater good". As it is, I put my efforts into making the books that I want to read. I'm willing to share that effort, but not to redirect it into making books I have no desire to read.
I, for my own use, format books for the platform I prefer to use. If I thought that others would benefit, I would occasionally invest a little extra time in making the book look especially nice, partly because I'm not really a terrible person, and partly because I might occasionally benefit from a similar effort from someone else. I don't see that there would be any harm in letting me do that.