Or just too large to grip.

Doesn't even have to be weight distribution. It's much easier to deadlift/clean something with a centered handle you cannot throw off balance than the same weight in something shaped even like a grabbable cube, let alone something large or uneven.

The quintessential example is a limp body. You could be strong enough to lift their weight over head in weights form, but as soon as it's a long sack of potatoes it can even be a struggle to get it on a shoulder.