While having the taskbar on the left works fine on single-monitor setups, I dislike it on multi-monitor setups where the taskbar is shown on all the screens. Typically I like having the taskbar mirrored on all my screens so I can access it easily wherever my mouse is. In this case the left taskbar ends up obstructing any windows that span multiple monitors.
Interesting! I'm running a three monitor setup and have the taskbar only on my most right display in the right side of the display, that way I have two entire displays entirely free for use and on the third display I think having the taskbar in the side takes up less space. (My displays are 16:9, 1080p each)
To me having the same thing on every display feels redundant. But that's probably just me, because my brother has the same setup as what you described.
Ultrawide monitors (I'm using the 49" Samsung Odyssey G9 at 5120x1440) would also suffer from having a taskbar on a side of the screen -- I currently have my Windows bar at the top of the screen, but honestly, the MacOS dock might be the best usability route for this monitor setup to keep things nice and centered.
