Any time they update and change the DRM there’s a brief period where newly-released amazon kindle books essentially cannot be read anywhere except kindle hardware and official kindle apps. People have pretty consistently found ways around the DRM (for now). But amazon is always trying to crack down on this.
It makes a lot of sense from a lock-in perspective, though I'm not certain why that leads to publishers insisting on it.
But hey, Grandma Martha can't read her Kindle version on the new Kobo her grandson got her without buying a new copy. Fantastic.
To the business-people making the kind of decisions we hate, that sounds to them like:
"So you're telling me grandma Martha is not rich, has no big team of lawyers, and they're taking down the agency advocating for consumers rights so no one can stop us if we fck her over and 200 million people more? Seems like it's her problem."*