I think you mean "show surprise" rather than "feigning surprise". "Feign" means "to pretend", while people who express genuine surprise are still "showing" surprise.
If anything, if one feigns surprise, they are acting in bad faith. I agree with the title of the article -- don't feign surprise, e.g. if somebody gives you a gift you knew was coming and pretend you're baffled by its appearance -- but do show surprise when someone you know who is intelligent is missing a small puzzle piece in their knowledge space.
Not in a belligerent way, of course, as the author points out: use it as an opportunity to educate. I ain't about to berate a friend of mine for not knowing something, but it would be quite disingenuous to hide my surprise; in my eyes, that's comparable to talking down to them.
The closest term to describe what the author meant is I believe a litote: https://en.wikipedia.org/wiki/Litotes
If a newcomer expresses genuine surprise, are they breaking the "No feigning surprise" rule or not?
edit: typo
I never know what to do when somebody goes through a lot of trouble to surprise me, but I figure it out anyway. Usually I play along and act surprised because it makes the other person feel good.
Imagine your girlfriend was planning a surprise birthday present for six months and somehow the secret leaked. You saw an open tab, or one of your common friends spilled the beans, or whatever. Are you going to ruin her excitement about surprising you just because "feigning surprise is bad"?
Usually in the form of "You don't know what X is?!" When someone asks an honest question.
It's pretty toxic behavior and I've found it typically comes from people less secure in their own understanding.
It's a shame because admitting ignorance and asking questions is hard for most people and one of the best ways to learn.
When people feign surprise it can scare someone into not asking.
Something I wrote about this a while back: http://zalberico.com/essay/2017/02/21/asking-questions.html
Julia talks about it in your quote above, but she says not to "act surprised", but she doesn't mean act as in fake, or feign, she means the action of expressing surprise. Another good reference is xkcd[0]. The point is not whether you're surprised, but the chilling effect that the judgment that someone should have already known this thing can have on their confidence, willingness to admit to not knowing things, and to the social dynamic of interacting with you.
The reason I mentioned it is that misusing a common term can be confusing and unnecessarily time consuming. As evidence, look at the response of bglusman above:
> It's not mentioned here, but when Recurse Center explains this rule to recursers, it's explicitly discussed that despite the name, it doesn't actually matter if you're actually surprised, it's still a "violation" of the rule to express that surprise in the particular terms of "I can't beleive you don't know about x!".
So in this case you have an explicitly written rule about feigning surprise, supplemented by an oral tradition that expands the rule to cover genuine surprise.
edit: soften, fix grammar
It makes perfect sense. If you suppress the urge to show surprise in these situation even when you are genuinely surprised, you won't feign surprise either. She's saying 'avoid showing surprise in that context altogether'. I don't see anything in there that suggests the writer didn't know what 'feign' meant.