To me it seems more efficient to have it on the left under the activities tab, since you already go there either by clicking or hot corner to get into the overview. It’d be a lot quicker with the mouse to just have the dock on the left side and only have to drag it down a few centimeters rather than dragging it all the the way to the bottom of the screen.
But since it is this way it is probably for a good reason, but where do i find the documentation for that? What led to this conclusion?
The layout of the Shell post GNOME 40 moved the workspace navigation from the vertical edge to the top third of the display; that required moving the dash from the opposite vertical edge to the bottom, to balance the layout and to avoid obstructing the workspaces.
The change was the result of multiple rounds of user testing: