So argues Cory Doctorow. He makes a point that also came up at the 1201 exemption hearings: the copyright owner does not clearly have the right to authorize a user to strip DRM from a work, where the copyright owner isn't the source of the DRM (and the major forms of DRM aren't operated by individual copyright owners). So Hachette can't, without some serious work, release a "read your Kindle books on a Hachette app" app. Obviously there are other issues, especially with the physical books, but it's a point worth considering.
Also the note that removing DRM from Kindle books is "literally a three-word search," despite over 15 years of the DMCA. As I've said before, the DMCA harms people trying to do the right thing and is irrelevant to people trying to do the wrong thing.