You can use this question to show your strength, you can say if its a one off situation you will go the distance but if its happening regularly then you will try to raise questions like why are projects always going into crunch mode, are we not estimating the tasks properly etc.

This shows that you are a team player but also willing to push back.

I indeed answered with something like this, still, they wouldn't have it.

Did it seem to you as if they "held that against you"?, I mean, that you said you'd work (a lot?) extra? Maybe they could look at that as indicating some lack of life experience,

Or was their intention with that part of the interview primarily informational, I mean, that they wanted you to get to know their company better?

They immediately told me it was a sort of trick question and explained why (they value my sanity and health). Perhaps it was also a way to advertise themselves to me? They sure made a good impression with this.

They made a good impression on me too :-) (via what you wrote)

If that's your interviewer or what the company wants then walk out. They've done you a favour flagging their toxicity.

Not in Europe because that would most likely be illegal.