The TouchBar's problem was both hardware and software. Because of its poor affordance for text labels it typically only allowed Mystery Meat UI[0]. If you labeled a button it ate up surface area and prevented a dense interface. Because it was constantly in flux you couldn't develop any muscle memory for it. It didn't help that the icons most apps used were inscrutable flat bullshit sigils.

It was made worse since desktop keyboards lacked the feature so you couldn't practice/learn the UI on anything but MacBooks. Keyboard shortcuts were far more useful since they worked on any Mac and whether or not you were using an external keyboard.

That lack of external keyboard support also meant developers couldn't write decent interfaces for the TouchBar unless they had the right MacBook. The simulator was not sufficient to actually test real world usage for positioning/ergonomics.

I found it to be a top to bottom failure of a feature. Small OLED screens on physical buttons would have been far superior ergonomically. Using the space for better cooling on the i7 and i9s would have been a much much better use of that space.

[0] https://en.wikipedia.org/wiki/Mystery_meat_navigation