Makes perfect sense to me. I have alot of calcium in my water already, so I use it. Never could understand why people pay to remove minerals so they can pay to add them back. I get it if the water is shit, but that isn't the case for 95% of people using RO. Oh well some people never learn.........
Just because one's water contains calcium doesn't mean it's in a form usable by plants, which is the case with calcium carbonate. So using RO is not just about 'removing minerals and paying to add them back'. People who know water are concerned with their alkalinity and the balance of minerals and RO is a way to start clean. Additionally, your water changes seasonally so unless you're getting a water analysis done every 4 months, you never know what's in your water unless you've run it through an RO filter.