This is less a question of behavior or functionality (“here’s how i use quote posts”) and entirely about semantics (“the nature of the relationship between my post and the quoted post is…”)
To use replies as an example: the functionality of replies is that you want to link your post to on or more posts in a series. But the semantics of replies is that you are specifically responding to the thing you are linking; the “link relationship” between “your post” and “their post” is “reply/response to”
@trwnh I would say the "the post being quoted" is embedded content within the "quote post", exactly like media or a link preview.
In all of those examples, the post is usually presumed to be "about" the content it's referencing. "Check this image/link/post out. here's what I've got to say about it."
Which makes it odd (to me) that the content being commented on is usually displayed below the text of the post. If I were designing from scratch I'd do the opposite.