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Explained: Why you can't move Windows 11 taskbar like Windows 10, according to Microsoft
(www.windowslatest.com)
What this essentially means is that when the taskbar sits at the bottom, Windows and third-party apps know exactly how much horizontal space they have to work with. Once you move it to the left or right, the math breaks.
Yup, engineers being paid six figures in their large corporate offices, controlling humanity's access to computers... hardcoded screen space sizes.
Of course this answer is also part bs because they don't want to let users move their taskbar because they should have to pay for that privilege.