Also gradually phasing out support of formats like mobi, in such subtle ways that if you open a mobi file you cannot go back to the library, but have to cold-reboot your device...

My current kindle is my third one, and is the last. I will never ever pay for a kindle to Amazon, due to its user hostility.

Oh, and also you cannot move ebooks between accounts, even not with a lot of friction, eg. support tickets, which would be a fair way to game piracy and unwanted lending, which was some inconvinience for me in a situation. Not a huge monetary loss for me, rather a reminder that when you pay to Amazon (or Valve, or any other contemporary DRM-burdened vendor) you are only leasing...