First of all: thanks for taking the time to respond to my necromantic response.
I can see some of the benefit of the classic editor, re: Micropub and the like.
Gutenberg is certainly a non-trivial system to support. Even the new block format seems like you really need to know how React works. That being said, it does allow for containerized HTML templates that can be extended. Not only in new blocks, but existing ones, too. I’ve mulled over the idea of extending certain block types (blockquote comes to mind) to have more microformat data embedded in it. That and add some features to the picture and video types. I just need the time and energy to do so.
Thanks for your time!