Talk about burying the lede!
"But leaving aside the revenue split, there are technical limitations as well. The existing in-app purchasing system in iOS has a technical limit of 3,500 catalog items. I.e. any single app can offer no more than 3,500 items for in-app purchase. Amazon has hundreds of thousands of Kindle titles.
"Something’s got to give here. I don’t know what, but there must be more news on this front coming soon. I don’t believe Apple wants to chase competing e-book platforms off the App Store."
In other words, all the rest of the article, defending the Apple terms, is so much codswallop. Because Gruber believes that these terms are unacceptable, as in Dead On Arrival, to major users of in-app purchases and will have to change shortly to accommodate them.
And once you have figured that out, why not apply this to the other users of the platform, the rest of these arguments? "Eating margins will chase applications off iOS" and "Catalog limits are too low for many credible use cases" apply to many more developers than just Amazon Kindle.
But for some reason these arguments are dissociated from the ones Gruber wants to make. Instead of putting together the whole picture, he comes to these major stumbling blocks and writes the equivalent of "Does Not Compute."