Carts are pretty awful to use, at least for hauling metal. It has some utility in hauling lighter like assorted mob drops, but it's very difficult to haul wood or more than a few stacks of metal. Flipped carts are a bit frustrating, as it has to be dismantled and rebuilt.

Sadly there are no pack animals to help with carts.

It's possible to harpoon a player and help pull them along, and thus get more strength into pulling a cart. It is possible to exploit carts by having a friend fill their inventory and sit on top.