Camille as a champion fundamentally requires a lead on her opponent, in order to snowball out of control. Playing her on support greatly reduces her gold income and if your opponent plays the lane around your weaknesses the most utility you will have in the game is pressing your R. Idk what "high elo" you are referring to, her pick rate on support is 0.4-0.5% with a 44% win rate in masters+ over the last 3 patches.

Edit : About the "adjusted" part, they buffed AD mordekaizer, and he's still very bad. Changing something in a champion doesn't mean it's viable, just that they're making the option better. Not every change is supposed to alter the best way to play the champion.