5th wheel configuration has a lot of advantages compared to trailer-hitch configuration. Stability, ease of maneuver, weight distribution, etc.

The "modern" way of greasing it is to "trowel" it on or I understand they make little bags of grease kind of like those laundry detergent capsules that you throw onto the plate then hitch up the trailer. (heard that in truck driving school but they didn't have us do much with connections other than drive them around the practice yard in reverse for many hours....)