Gruber’s position is that Apple shouldn’t care, because they don’t “need” Readability. But they most assuredly do, in the aggregate; Apple needs Readability, and Pandora, and Netflix, and Instpaper1, and Rdio, and all other businesses put in a precarious position by Apple’s new rules. Apple needs them because a large part of the platform’s value is in having access to all kinds of media and services.
This isn’t just because it’s nice to have Netflix and Pandora: it’s because the iPhone and iPad’s magic is the idea that it becomes whatever application you’re using. What good is it if you can’t use a number of services that you really love using? Not much. The iOS platform will become dramatically less useful and exciting if there are only a limited number of services available.