Lessons from Gutenberg

The codebase of Gutenberg is difficult for all of us, because no one in the wpa11y team is a skilled React developer. So it was hard to implement changes and write PRs ourselves. What we could do is test, tell what’s wrong and what it should be and hope a developer would pick it up. A lot of a11y work has been done by the Gutenberg team but major issues still exist.
…
The results indicated so many accessibility issues that most testers refused to look at Gutenberg again.
—Rian Rietveld

Note "a11y" means "Accessibility", because of course we don't write it all out.

All of this suggests that Gutenberg was pushed out because it was useful in business competition with SquareSpace, not because it helps any WordPress users. The classic rich text editor was fine for many newbies, and then they'd graduate to HTML or Markdown, neither of which are rocket surgery, when they needed more control.

Despite my heavy use of JavaScript, I've never touched React. It seems to be an attempt to combine a native UI model with web rendering, which is an utterly alien environment. But there are minimal React a11y guidelines; many of these seem tedious to implement, like those dropdowns, but not impossible. This likely would've gone better with static HTML and normal JS controls where necessary to create blocks.