Some forums have this option and I think it can be useful if you are out of the loop with some threads and you are not sure what's the entire context of the reply/post some users are making.
Example:
POST
User replied:
Post
Yeah, I agree.
I think there should be a button ( I mean like an arrow or smth like that) next to the quote(or something like that) that if you click will lead you to the original post that's being quoted.
Just an idea :)