Dude, Where’s my WordPress Visual Editor?
I had a new install of WordPress with a manually added user, and ended up in a state in which I couldn’t enable (or disable) the WordPress visual editor or add blocks to my posts.

It turns out the manually added user that I was using was missing a nickname and the user profile changes wouldn’t save.

Once I added a nickname, I was able to save and toggle the Visual Editor setting and now I magically have blocks and a visual editor.