Huge advantage of the start button on the bottom left: I can just “throw” my mouse pointer as far down and left as I can and click, and I’ll always hit the start button.
"Placing layout elements on the four edges of the screen allows for infinitely large targets in one dimension and therefore present ideal scenarios. As the user's pointer will always stop at the edge, they can move the mouse with the greatest possible speed and still hit the target. The target area is effectively infinitely long along the movement axis. Therefore, this guideline is called “Rule of the infinite edges”. The use of this rule can be seen for example in MacOS, which places the menu bar always on the top left edge of the screen instead of the current program's windowframe."
[0] https://en.wikipedia.org/wiki/Fitts%27s_law#Implications_for...