As always, bold statements require equally strong evidence. You dont provide any.
Sarevok can only be interacted with for the very first time when you return to Candlekeep in Chapter 6. Plus its a bad idea to interact with him at that point, and even if you do, he doesnt have much to say except complete lies. So really your only true interaction is at the very end of the game, right when you actually fight him.
Before that you only see him at the game start and when he murders Gorion. Cutscenes that we can only watch passively.
So yes, Savevok doesnt really appear until the end, and he never has much to tell you either. For the majority of the game, he's just a shadow hanging over you.
If thats indeed "One of the best villains ever", well then you dont have very high standards in that regard at all.
AD&D is literally nothing but quirks. Just looking at the attribute tables, universal principles like D&D5 proficiency are completely unknown. The really only time two attributes ever have the same effect is to my memory when it comes to the Lore bonus you get from Wisdom and Intelligence. Otherwise everything gets their own logic and so many details are completely arbtitary and follow no logic, internal or external, at all.
