Just today I had the disk usage analyzer (baobab) open and I was navigating inside directories so I want to go up a directory and clicked on the "<-" left arrow in the headerbar, which went "back" a screen, discarding all the work done scanning the filesystem.
If this app had a traditional menubar and a toolbar this wouldn't have happened.
This is a common type of experience I have every time I use a Gnome app. It almost feels like someone deliberately researched how to make desktop apps as counter-intuitive as possible and implemented that as the policy for some reason.
And locked your thinking into the OS' way of thinking. Every software vendor had to do their application a few times over with a different release for each OS, because the design is completely different.
As someone who uses multiple OSes (work macOS and iOS, home Windows and Ubuntu, Android) I hate nothing more than apps that behave differently on the different OSes, with different logic or features.
In the early days, if you learned the OS, those usage patterns and skilled transferred to every app on that OS. They all looked roughly the same, shared the same menus, shame shortcuts, same icons, etc. You didn't have to learn how to use Apps x, y, and z. You just had to learn Windows (to an extent).
Then marketing got involved, and then the web, and then suddenly every piece of software had to stand out and look and behave as unique as possible, throwing years of HIG research out the window.