Deere calls theirs a "coulter cart". One advantage is that you can add no-till capabilities to a conventional 3ph drill or planter. Also, a smaller tractor can be used in some situations since it takes a lot of heft to lift some of these drills and planters.

Many of these carts have the ability to carry liquid starter fertilizer. It's cheaper and less cumbersome than towing another implement behind the planter or drill.