The point is to STOP consuming artificial sweeteners. Sugar itself has a long Conspiracy history as well. Use your search engine to find out about these and after you've read 10, 50, 100s and 1000s of studies it becomes clear. I personally don't use stevia, but many different groups and studies have disproved the safety of artificial sweeteners.
Think about it, no one has argued that Diet Soda is "GOOD" for you, so doesn't it just show common sense that anything not GOOD for you would naturally be BAD for you?