I recently worked on an admin project with a group of varying experience and grade, from months to decades using MS Office. It's the first time in years I've had to use 'ribbon' apps.
Not one of the staff used the ribbon directly, they just searched for everything using Word's titlebar search field and picked the option from the results. Every time, unless it was something like embolden that has a keyboard shortcut.
I tried hunting and pecking through the ribbon but it was such a guessing-game, trying to imagine where the UX designer had filed the option, that I eventually relented and started using the search field too.
That's the problem. Toolbar buttons ought to be ONE-click shortcuts. Menus are multi-click.
My frustration stemmed primarily from having to constantly bounce back and forth between toolbar tabs to get certain tasks done (it's been a while so I can't remember the exact use cases, maybe formatting table borders and fonts/bold/etc). In those cases it legit doubled my clicks.
The ribbon essentially took my menus, and made them waste vast amounts of precious vertical screen real estate - not to mention less consistency in presentation & discoverability (particularly when other software I wasn't as familiar with began to copy the trend).
If I recall, older versions also did a better job of surfacing keyboard shortcuts (via tooltips), so you would inherently learn the ones you used most as you used the software.
I came from the old school, and am still powering along through professional studies and office work as a relative power user.