Who will make these apps for the new platform? They have no need to develop for a new platform in hopes it becomes popular, and very few of them have open APIs for the platform to make their own third-party apps.

But they do need editing, layout, design, marketing, etc, which are a significant part of the cost of a book. A book is never a solo endeavor by an author.

Publishers aren't just stealing money that should go to authors. We can debate percentages and such, but buying a book also pays the editors (who any author will tell you are just as important to a book as they are), the typesetters, the designers, etc.

These days I use emacs for most of that stuff, but I have such a fondness for BBEdit, and still drop into it for regex stuff enough, that I'm buying the update.

The point that the person you're replying to is making is that this totally breaks the way libraries have always worked, and that it takes a lot of power away from the buyers (whether that's you or your local library) and puts way more in the hand of the publishers.

It doesn't really matter to me whose fault it is. Basically no one is using Obsidian without plugins, and the impact plugins have on your portability is something to consider when choosing to use Obsidian.