I have an alt who I am using for farming, and as my farms are getting bigger and bigger I have noticed I am reaping little XP for the effort required for the process. It feels like it should be at least double for harvesting since I understand having nothing for planting due to griefing.
It just seems a little unbalanced for the effort put in, you should gain more XP for farming than just collecting gleam, since you have had to make the time to learn and make the farms as well as plant and wait rather than just regening.