Since I'm the guy that stated, lubricate liberally in the stated thread I will state my case.
Nowhere in my L3901 manual do I see any mention of lubing the 3 point balls or linkages, and on my previously owned B7100 I also kept them lubed. I lube my 3 Pt balls, pins etc. with a mixture of 30 wt. motor oil and Marvel Mystery oil, same stuff I have always lubed the door hinges on vehicles with, a concoction from an old mechanic I met. When I detach an Implement I wipe the balls and pins with a rag and re-oil.
Why I lube, 45 years in industrial maintenance and a lot of rusted worn out machine components because the person responsible for lubrication did not want to do their job. In my experience lubricate, it's cheaper than parts, labor and down time. I will also go a bit father and use the advice my Father gave me years ago, he was a power shovel and loader operator in a large gravel pit, keep it lubricated. The damage done to pins, bushings and bearings by neglecting lubricated will become very evident in a short period of time. He found out after a two week vacation when another operator ran his equipment, it was not lubricated and required many thousands of dollars in materials and labor to repair the damage. We as tractor owners do not have a corporate account to repair our equipment, if in doubt lubricate it.
I agree that lube does capture dust and dirt. But a dry ball joint will also attract dust, dirt and moisture. I believe in this application most of the dirt will be captured by the outer film of lubricant, and what does get into the center of the ball will be held in suspension thus causing less wear because of the lube. Lubricant is also very good at dispelling or limiting the egress of moisture and oxygen on metal surfaces the major causes of rust.
For what little I think these ball joints move I do not believe a little dust or dirt that gets into them will wear them as fast as dry rusting similar metals. My lift arms may sit on the shelf in the barn for weeks at a time while the BH is mounted and with a film of oil they are always free and seems to slide on to the implements pins easier when mounting. Those that are using there 3 pt. hitch frequently as stated may never have and issue, but how many of us use our 2 point hitch every day. Also, we are not rotating these ball joints for hours or under conditions as would be done with a lapping compound which has some very hard silica imbedded in it.
After some further online research into the question it reminded me of my own practice of spraying silicone on hydraulic cylinder rams. I do believe that a silicone or similar spray may work well in this application resisting the cling of dust/dirt and provide a protective film from moisture. I have always sprayed hydraulic cylinder rams on my tractors and the leveling cylinders on my motor home with silicone to keep debris from clinging to the shaft and being ingested into the cylinder shaft wiper and seals causing potential hydraulic leaks. I my give this a try and see what results I get.
Maybe a tractor owner who runs his tractor for 10-12 hours a day, 6-7 days a week making a living will chime in with their thoughts and practice, to me that would be the ultimate testimonial.
Thanks for reading my point of view, looking forward to reading your comments.