I was joking. You can nerf viper.
However, to have a balanced agent pick rate, it's not enough for agents to be at similar levels. You also need variety in maps. You need to make maps so that different agents are suitable on different maps. Otherwise, pros will start moving towards a few agents again after a while. Then you nerf again, and the cycle continues until all the agents have weaker abilities as time goes on.
The bigger issue in Valorant right now is the difference in value between movement duelists and non-movement duelists. Movement is valuable on every map, and flash initiators offer more value than flash duelists - leading to extremely low pick rates for flash duelists.