Amazon did this. It did it for one reason, and one reason only: to advance their proprietary hardware platform, the Kindle, at the expense of Apple's platform, the iPad and iPhone. They have deliberately degraded the iPad and iPhone Comixology app so that users of the Kindle will have a better reading and purchasing experience. That's all this is about. They've destroyed the future of digital comics to give an advantage to their hardware platform — and, in passing, to leverage their control of digital comics distribution to do to comic book stores what they've already done to brick-and-mortar book stores.
Now, I've heard some folks say that Amazon is just trying to avoid paying Apple's "greedy 30% fee" for in-app purchases. This is such nonsense it almost doesn't require a response, because there are people out there who have a knee-jerk reaction against Apple that goes beyond critical thinking, but in the hopes of reaching more open-minded readers who might be tempted by that argument, let me address it.
Apple charges 30% for in-app purchases of eBooks, music, video, games. Amazon charges 30% for digital distribution of eBooks, music, video, games. Same deal. Period.
There's a long and fruitless debate to be had over whether or not Apple "deserves" to make a profit off its App Store. Anti-Apple deniers say no, and their arguments usually boil down to just a dislike of Apple making a profit (or what they consider a "greedy" profit). The fact is, Apple provides a storefront for developers to sell their apps, and as any store owner would, asks for a piece of the money the developers make as a result. Mall owners ask store owners to pay rent. It's a normal business transaction. Happens every day. Apple's App Store provides developers with access, and gives them three ways to pay for the privilege: developers can charge for the app directly (and Apple takes a cut, 30%, same as Amazon); developers can provide the app for "free" and Apple will place ads in the app (ad-supported payment, like Google search); or developers can offer in-app purchases (and Apple takes their 30% cut, one step removed).
What Amazon is doing is finessing Apple's deal with developers by providing an app for free, yet not paying Apple's fee for the privilege. In effect, Amazon is a store owner in a mall who isn't paying rent to the mall owner. And anti-Apple deniers think that's fair, why? Because they just don't like Apple making a "greedy" profit. But it's okay for Amazon to make that same "greedy" profit while taking advantage of a loophole in Apple's deal with developers. To me, this is blatant hypocrisy or blind economic naïveté. But believe me, Jeff Bezos knows exactly what he's doing: he's screwing Apple, and he's screwing the future of comic books. If you let him get away with it because of some bizarre anti-Apple bias, you're screwing yourself, too.