There is a big difference between toxic and overpowered. While they often go hand in hand this is not always the case. None of the various Spellhai decks are overpowered but they are extremely toxic. Rag is the opposite.
Toxic=A lack of significant counter-play, interaction, solitaire style play, and or unhealthy RNG. Egg Rag pings basically none of those. That being said he has by far the most raw power of the top four, which gets evened out with the others due to various counters, lots of counterplay, and probably the highest skill cap.
Extra Ironic due to the fact that Burn Ziran hard counters him and he has an abysmal win rate vs her. Excess pings/aoe makes killing eggs easy, the ease of buffing her atk makes ripper combos useless, and her speed makes lategame options like finality and or extinction not really feasible. And she does not even pack provokes which is another common way of dealing with him.