People who have to regularly take half a pill sometimes struggle with breaking the pill into clean halves, or don't like having to use a kitchen knife or whatever and clean it later.
In fact the opposite happens here, you end up with instructions like "Take ten", each of which has to be individually popped out of a blister pack.
Another comment mentions Metformin. This is more of a hassle since I find the 1g tablets awkward to split with my pill splitter due to the size, and yet for some reason finding the 500mg version is rare for me.