Why is something or someone deemed unimportant referred to as being “just a footnote” when footnotes tend to refer to significant earlier works that support an argument?

Question

Why is something or someone deemed unimportant referred to as being “just a footnote” when footnotes tend to refer to significant earlier works that support an argument?

In: Culture

Answer 1

Because that’s just it, they are relevant PAST works, never the work being read, only referred to and linked at the end/outside the text.

The rude element being that you are not the focus, merely something on the outside.