Hi
I am a web designer myself and use wordpress to build my clients sites and have been using different themes (most of which have the option to use their own editors if you want to build something more complex). I didn’t even try to use Gutenberg in sites with posts I have created with their own editors.
I tested it in news sites I support where multiple authors – mainly journalists – who write many posts everyday, posts we have decided how they should look sitewide through settings and NOBODY liked it. They like to sit down and write and not be bothered with designing. I thought that this was the main thing with wordpress. Blogging. Gutenberg focuses more on designing.
I hope I was clear enough – English is not my native language. Thank you.