* Inserting special characters: personally I don't find those "character choosing" windows to be very convenient. Hunt and peck is a slow way to type! Anyway, you can do this in Markdown with either Unicode (if you have the right keyboard) or you can write HTML escape codes (&tm; etc.)
* Automatic (grammar/spelling). I don't like check as I type, but sure. Anyway, Emacs provides this if I want it.
* Macros. Hello? Emacs? (Also, Pandoc has a scripting interface.)
I may not be published yet but I've written my own book. I've also published books for other people. I did both of those with a Markdown-based toolchain. It works.
The "inserting special characters" one is a bit of a "eh?" for most of us Mac users, I think, since most special characters can be typed using the Option key and the character chooser (which is indeed not very convenient!) is system-wide and should work in a native build of at least the GUI version of Emacs. But, yep -- Markdown and Word aren't the same categories of things. How comfortable your Markdown editing experience is depends on how comfortable your Markdown editor is.
(Also, I wrote a Markdown-to-ePub script, too! Although I don't think anything I've got up online uses it anymore.)
* Inserting special characters: personally I don't find those "character choosing" windows to be very convenient. Hunt and peck is a slow way to type! Anyway, you can do this in Markdown with either Unicode (if you have the right keyboard) or you can write HTML escape codes (&tm; etc.)
* Automatic (grammar/spelling). I don't like check as I type, but sure. Anyway, Emacs provides this if I want it.
* Macros. Hello? Emacs? (Also, Pandoc has a scripting interface.)
I may not be published yet but I've written my own book. I've also published books for other people. I did both of those with a Markdown-based toolchain. It works.
Edit: Just to prove the point: https://www.amazon.com/dp/0692553916 . Go see for yourself how the book is formatted.