Once simple example: One site has a section for posting PDFs of meeting minutes. I use a separate plugin for handling those. Under the previous documentation, she simply created a new post, gave it a title, clicked the document area, clicked the icon to upload media, uploaded the PDF, and she was done.
Under the new system (which I can’t replicate now to give you the exact steps because I installed “Classic Editor” on all my sites), it took three or four additional steps for her to even be able to get to the point where she could even upload a PDF, and that’s not including explain how she’d need to click in the exact right areas to even make the necessary buttons appear. And then, once she did, it ignored the tags of the PDF embedding plugin and just made download links for the PDFs instead of displaying them inline. I discarded everything I wrote, installed Classic Editor, and everything was back to easy, smooth, and working perfectly.
Gutenberg should have remained an optional add-on for the handful of people who for whatever reason prefer editing documents in a way that is entirely counter-intuitive, cumbersome, and takes far more time. It should not have been forced on the masses who are perfectly happy with creating documents the simple and easy way that everyone has been familiar with for decades.