Why is "would" used in this sentence?

Question

I’m a passionate English-learner from Korea, and I have a question.

Why is would used in this sentence?

A true friend would not say such a thing.

I can think that the speaker is probably not saying that a true friend in general “doesn’t” say such a thing. So, I think maybe the sentence means this sentence:

If you were a true friend of mine, you wouldn’t say such a thing.

My point is that I think the “a true friend” doesn’t actually indicate a true friend in general. I think the “a true friend” indicates the listener. And so I think that’s why would is used to refer a simple, imaginary situation. Is this why would is used instead of does here?

I would really appreciate your help.

Answer 1

I am going to expand on JD2000 comment

When you say I think maybe the sentence means this sentence. : If you were a true friend of mine, you wouldn't say such a thing that's exactly it - but this does not mean that " "A true friend" doesn't actually indicates a true friend in general. I think the "A true friend" indicates the listener." It indicates a hypothetical person and the point is that the listener has not behaved like that hypothetical person i.e. a true friend would not say X, but you did - you are not a true friend. – JD2000

with an example conversation

Pretend Friend 1: you are a miserable cow, who needs to get over your fathers death it was hours ago.
Friend 2: A true friend would not say such a thing.

Friend 2 is saying that friend 1 is not a true friend, as no true friend would say such a mean horrible thing.