Funny that this doesn’t even mention the actual critical failure of CSS centering: data loss on all items overflowing to the left of the container. Items to the right can be scrolled into view, but items to the left are entirely inaccessible.
Is that any worse than an inability to scroll up, vertically negative, from the initial scroll position?
But I suppose the complaint might be able to be generalized to all items past the start of a main-axis centered flex-box. Doesn’t make the failure more excusable.