I would have hoped when you disable the visual editor in your user profile, that would have disabled it site-wide. That’s why I disabled it in my user profile so I could actually create the code I wanted for the sidebar, particularly with the tooltip effect I wanted.
With this I had to copy and paste from another site I had with the same coding that I hadn’t updated to 4.8, then put in the coding I’d attempted to put in on the site I’d updated, then in order for the changes to take effect you have to switch back to visual from text mode. Pain in the behind. There is a reason I hard code and shut off the visual editor on the site. I don’t need it imposed in an update we’re sort of forced into taking due to security issues, but no power to shut off the features we don’t want.