Some of the spindles on Cubs have sealed bearings and do not have zerks. Some Cub spindles have sealed bearings and DO have zerks that are useless. Some Cubs have spindles that have zerks that are way up inside the center of the spindle where it is impossible to get to without removing the deck and flipping it upside down. I think it's all a matter of what Chinese spindle supplier had parts on the shelf at MTD when they built your mower.
Mine has the "impossible to get to" zerks. They get greased maybe every other season or whenever the deck has to come off for something. If I never have to remove the deck, I'll just run the spindles to failure.