The heaviest current draw from the battery is the starter motor, so on many cars, especially older cars, the negative cable attaches to a starter motor mounting bolt, which provides the least resistance path back to the battery.
Such a wiring scheme would also require a good ground between the engine and the chassis to ground the various lamps and accessories. The alternator usually grounds to the engine through its mounting brackets.
In a case where the battery ground cable connects to the chassis, you should also find a substantial ground cable from the engine to the chassis to handle the 100-200 amp draw of the starter motor, and the up to 120 amps from the alternator.
Most cars usually have more grounds than absolutely necessary for electrical continuity. The extra grounds are usually there to reduce electro-magnetic interference that can be caused by high loop currents.