Because remineralization doesn't actually work? Makes perfect sense to remove the minerals just to add them back. Many water treatment companies suggest that

Because remineralization doesn't actually work? Makes perfect sense to remove the minerals just to add them back. Many water treatment companies suggest that because reverse osmosis systems remove the minerals from water that you should add a remineralizing filter afterwards for the purpose of restoring minerals to your water. I’ve tested these filters and while the pH rose dramatically due to carbonates in the filter there were no minerals added. A number of companies use coral calcium as the remineralizing filter and it is true that coral calcium contains some 70 trace minerals. The problem is that the water passing through a filter system is not in contact with the coral calcium long enough to dissolve it. The water picks up carbonate and as a result the pH increases but essentially no minerals are added. You might see trace amounts of calcium and magnesium.