I think there's two different things going on here. What you talk about is very much real -- the standard "how's it going?" or "how are you?" American question/response ("Good! You?"). Answering that sort of question in the way you suggest is a fairly non-American thing.
But I think there is also a more specific founder/startup conversation that Sam refers to -- that's more like this:
Q: "Hey, how are you?"
A: "Good! You?"
Q: "I'm good. So how are things with the company? How are you guys doing?"
That's where the typical "Oh we're killing it!" is coming in and where it might be nice for some to be a bit more honest. "We're trying. It's a struggle." You can also learn a lot about the person you're talking to by seeing how they respond to this. The good ones are the ones who respond with empathy and who want to listen.
But I think there is also a more specific founder/startup conversation that Sam refers to -- that's more like this:
Q: "Hey, how are you?"
A: "Good! You?"
Q: "I'm good. So how are things with the company? How are you guys doing?"
That's where the typical "Oh we're killing it!" is coming in and where it might be nice for some to be a bit more honest. "We're trying. It's a struggle." You can also learn a lot about the person you're talking to by seeing how they respond to this. The good ones are the ones who respond with empathy and who want to listen.