I think the grandma case is just made up. I've seen older people use win11 just fine, they aren't so incompetent that they can't click a button on their task bar. If they are having trouble with that, then even if they could get to the windows button easily in the corner, they'd have a tricky job clicking any of the things that come up in the windows menu which are all the same size, and now, not even aligned to the bottom edge of the screen! Poor Grandma :)
Also on big screens the centered taskbar is great