I agree that Surgeon is on average the worst card in the deck. It's rare that an effect is worth loosing 2 sigils for. I did some statistical analysis using a small sample size (Less than 50 games) of top level games a month ago and when checking for winrates, given that a card was discarded from Assassin, Surgeon had by far the best. Meaning that if your opponent would start the game without assassin and you would in turn have to remove any card from your deck, removing surgeon would be your best bet.
There are a few other uses besides the ones you mentioned though:
- Guaranteeing the play of void mage, this can be important in some situations if the opponent has a very strong judge
- Getting a Judge or Swamp Guardian off is also okish
There is also the mind game component. E.g. you expect an Assassin and play Surgeon to counter it, or playing surgeon after the opponents surgeon to get a draw versus their Judge.
You also need to keep in mind, that in this game everyone has the same cards. So it's less about playing "good" cards and more about making the best out of your cards. Because while you might have to play surgeon at some point, so does your opponent. If e.g. the opponent wins against my Surgeon with his Inventor and I win against his with my Mediator, I would have used my surgeon more "efficiently".
But beside that, if I know the Opponent is playing Assassin (Due to Fortune Teller), I will always (probably) play Surgeon if I can
