In reply to Nick.
With shortcodes, it’s no so much the insertion that is the problem (although that can be an issue), it’s more people deleting a square bracket or part of an attribute that stops something working.

e.g. Many people insert their Forms via a shortcode, which is an incredibly fragile way of doing things.

Besides, having square brackets with cryptic codes inside makes it look like WordPerfect circa 1990 to someone non-technical!

I’m sure it would be easy enough to write a plugin to revert to TinyMCE if they don’t offer Gutenberg as an option in the first instance.

I can see some negatives to Gutenberg, but I think at this stage constructive criticism is what’s called for to make a promising start into an awesome finish.