Thanks for all the replies everyone I really didn't expect it to get this spirited on this subject. But I'm glad people on both sides of this answered.
LOL for whatever reason this is contentious topic. Does it need it... probably not, does it hurt it..not at all. A catch can is just the term the automotive industry uses for a coalescing filter, they have been used in industry to filter oil out of compressed air systems for decades. Like
@19reb said the PCV system is designed to vent the crankcase of un-burnt gasses that blow by the piston rings during normal operation and is part of the emissions control system, prior to the 1960s they used a draft tube to scavenge these gases and vented them to the atmosphere. Inevitably oil vapor also gets entrained in the gases and the coalescing filter "catch can" removes the oil vapor by coalescing it back into a liquid. Does it affect performance and efficiency, likely nothing significant to move the manufactures to install them from the factory, even on DI engines where catch cans actually have a larger impact. Due to increasingly strict CAFE standards bringing up fuel economy is obviously high on the priority list, think about the all the time and money manufactures have invested in engine technology to improve fuel economy, multi displacement, turbo charged 4 and 6 cylinders, e-torque, ram even went so far to design a secondary air-dam that drops down above 35 mph to pickup just fractions of an MPG. The added weight and R & D costs involved from any of these systems is significantly higher than an aluminum catch can. Logically, if there really were any significant gains to performance or efficiency you'd see these things on every truck rolling off the assembly line.